首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2270篇
  免费   132篇
  国内免费   20篇
耳鼻咽喉   35篇
儿科学   24篇
妇产科学   36篇
基础医学   320篇
口腔科学   37篇
临床医学   182篇
内科学   625篇
皮肤病学   47篇
神经病学   221篇
特种医学   71篇
外科学   324篇
综合类   7篇
预防医学   87篇
眼科学   76篇
药学   126篇
中国医学   1篇
肿瘤学   203篇
  2023年   9篇
  2022年   30篇
  2021年   62篇
  2020年   43篇
  2019年   42篇
  2018年   55篇
  2017年   33篇
  2016年   40篇
  2015年   57篇
  2014年   75篇
  2013年   105篇
  2012年   145篇
  2011年   146篇
  2010年   78篇
  2009年   72篇
  2008年   144篇
  2007年   122篇
  2006年   126篇
  2005年   156篇
  2004年   121篇
  2003年   125篇
  2002年   125篇
  2001年   39篇
  2000年   50篇
  1999年   41篇
  1998年   20篇
  1997年   17篇
  1996年   13篇
  1995年   12篇
  1994年   17篇
  1993年   18篇
  1992年   15篇
  1991年   16篇
  1990年   14篇
  1989年   9篇
  1987年   12篇
  1985年   10篇
  1984年   10篇
  1981年   7篇
  1980年   11篇
  1979年   6篇
  1977年   9篇
  1976年   8篇
  1974年   8篇
  1972年   7篇
  1969年   7篇
  1929年   6篇
  1924年   11篇
  1923年   6篇
  1922年   6篇
排序方式: 共有2422条查询结果,搜索用时 15 毫秒
1.
2.

Background

Treatment of advanced anal squamous cell cancer (SCC) is usually with the combination of cisplatin and 5-fluorouracil, which is associated with heterogeneous responses across patients and significant toxicity. We examined the safety and efficacy of a modified schedule, FOLFCIS (leucovorin, fluorouracil, and cisplatin), and performed an integrated clinical and genomic analysis of anal SCC.

Patients and Methods

We reviewed all patients with advanced anal SCC receiving first-line FOLFCIS chemotherapy – essentially a FOLFOX (leucovorin, fluorouracil, and oxaliplatin) schedule with cisplatin substituted for oxaliplatin – in our institution between 2007 and 2017, and performed deep sequencing to identify genomic markers of response and key genomic drivers.

Results

Fifty-three patients with advanced anal SCC (48 metastatic; 5 unresectable, locally advanced) received first-line FOLFCIS during this period; all were platinum-naive. The response rate was 48% (95% confidence interval [CI], 32.6%-63%). With a median follow-up of 41.6 months, progression-free survival and overall survival were 7.1 months (95% CI, 4.4-8.6 months) and 22.1 months (95% CI, 16.9-28.1 months), respectively. Among all patients with advanced anal SCC that underwent sequencing during the study period, the most frequent genomic alterations consisted of chromosome 3q amplification (51%) and mutations in PIK3CA (29%) and KMT2D (22%). No genomic alteration correlated with response to platinum-containing treatment. Although there were few cases, patients with human papillomavirus-negative anal SCC did not appear to benefit from FOLFCIS, and all harbored distinct genomic profiles with TP53, TERT promoter, and CDKN2A mutations.

Conclusions

FOLFCIS appears effective and safe as first-line chemotherapy in patients with advanced anal SCC and represents an alternative treatment option for these patients.  相似文献   
3.
Apoptosis is an essential ubiquitous process that controls the duration of the life span of cells, thus playing a crucial role in morphogenetic, histogenetic, and phylogenetic developmental processes. Apaf1 (apoptosis protease activating factor 1) is one of the central mediators of the intrinsic apoptotic pathway and a part of the apoptosome, which activates procaspase-3 and promotes cell death. Gene knockout of Apaf1 in mice leads to late embryonic lethality with malformations such as the persistence of interdigital webs and hyperplasia of brain and retina. Therefore, Apaf1 is generally believed to play a crucial role in developmental apoptosis and have a widespread expression. However, its pattern of expression in early development remains unknown. To specify whether Apaf1 indeed plays this key role, we investigated the pattern of gene expression for Apaf1 in mouse embryos on day 7, 9, and 12 of development. Our results show, that gene expression for Apaf1 first occurs within the embryo between day 7 and 9 of development, becoming more widespread toward day 12 and then includes structures, such as yolk sac, mesenchyme, cartilage, heart anlage, otic vesicle, peridermis, and anlagen of the spinal ganglia and vertebral bodies. Our results also show that gene expression for Apaf1 is not ubiquitous in early mouse development. This finding indicates that cell death processes are independent of or less dependent on Apaf1 during this time. Of interest, an active gene expression for Apaf1 is also present in organ anlagen such as heart or intestine, in which no obvious phenotype is seen after Apaf1 deletion. This finding suggests a possible role for Apaf1 in such anlagen as a putative alternative compensatory pathway, which could be switched on in the case of defects in the mediators that are normally involved in such organs.  相似文献   
4.
Background: Sudden, intraoperative cardiovascular deterioration as a result of pulmonary embolization of bone marrow fat is a potentially fatal complication during total hip and knee arthroplasty, intramedullary nailing, and spine surgery. Anesthetic management is challenging in the presence of increased right ventricular afterload due to pulmonary hypertension. Selective pulmonary vasodilation may be an appropriate prophylactic or therapeutic measure. The effect of sildenafil (phosphodiesterase inhibitor) on cardiovascular deterioration after bone marrow fat embolization was therefore investigated.

Methods: Bone cement (polymethylmethacrylate) was injected into three lumbar vertebrae in 12 sheep. Invasive blood pressures and heart rate were recorded continuously until 60 min after the last injection. Cardiac output and arterial and mixed venous blood gas variables were measured at selected time points. Before the first cement injection, 6 animals received a bolus injection (0.7 mg/kg) of sildenafil, with continuous infusion (0.2 mg [middle dot] kg-1 [middle dot] h-1) thereafter. Postmortem lung and kidney biopsies were taken for semiquantitative analysis of intravascular fat.

Results: Fat embolism was associated with a transient increase (21 +/- 7mmHg) in pulmonary arterial pressure. A transient decrease in arterial blood pressure and temporary increases in central venous pressure and dead space were also observed. No significant changes in any cardiovascular variable were observed after fat embolism in the sildenafil group. There was significantly (P < 0.05) less intravascular fat in the lungs of the sildenafil (median count of 5 emboli per microscopic view) compared with the control group (median count of 1).  相似文献   

5.
OBJECTIVE: As more patients are diagnosed with prostate cancer at an early stage, it is becoming increasingly important to refine the technique of surgical excision. For this purpose we have generated objective data comparing three different surgical approaches used by three experienced surgeons. METHODS: We prospectively compared three contemporary personal series of 50 consecutive radical prostatectomy (RP) patients. The health-related quality of life was evaluated preoperatively and in months 1, 3, 6, 12 and 24. RESULTS: Considering in turn the patients undergoing retropubic, perineal and laparoscopic RP, the median procedure time was 2 h and 27 min, 1 h and 50 min and 4 h, with a transfusion rate of 2, 0 and 8%, respectively. In the perineal group there were more wound infections. Median catheter drainage was 7, 10 and 7 days and zero, 13 and one patients needed reinsertion of a catheter. Early continence varied considerably, with 57.4, 11.4 and 6.3% of patients pad-free after 1 month, but there were no differences in social continence (zero or one pad) with 97.8, 97.8 and 91.9% after 2 years. The Litwin score for incontinence (preoperative minus postoperative) was -24, -41 and -63% after 1 month and -13, +3 and -29% after 2 years. Twenty-nine, five and 15 patients had a preoperative five-item version of International Index of Erectile Function (IIEF-5) score of > or = 17 points and a nerve-sparing procedure. After 2 years, 48.1, 0 and 0% had an IIEF-5 score of > or = 17 points without the use of phosphodiesterase type 5 (PDE-5) inhibitors, but when including patients using inhibitors there were no significant differences. CONCLUSIONS: A comparison of morbidity, short-term convalescence and long-term side-effects of different surgical techniques is strongly biased by both the preoperative status of patients and the skill of the surgeons. Overall, we found some differences in the short-term results (e.g. early continence) and comparable long-term results.  相似文献   
6.
BACKGROUND:: A soluble 105 kD neu-related protein is detectable in conditionedmedium from breast cancer cells expressing the neu-oncogeneproduct and in serum of nude mice bearing tumors that overexpressneu-oncogene PATIENTS AND METHODS:: In 100 patients with primary (n - 33) relapse-free (n - 6) andmetastatic (n - 61) breast carcinoma the serum levels of thesoluble new-related protein were investigated by ELISA techniques.Median age was 57 years, range 26–89 years. RESULTS:: The neu-protein serum levels were below 40 HNU/ml (human neu-antigenunit) in 72 patients and 40 or more HNU/ml in 28 patients. In30 patients with primary breast carcinoma, tested before mastectomy,all serum- neu-protein samples were negative. However, 26 of61 metastazised patients (43%) were serum-neu-protein-positive.In disseminated disease (n – 61), serum-neu-protein-positivitywas more likely to be seen in patients with visceral metastases(18/33 – 54%), than in patients with nonvisceral metastases(8/28 – 28%). Furthermore, monitoring of the serum-neu-proteinlevels reflected clinical course. For 53 patients original paraffin-embeddedtumor material was available for studying immunohistochemicalneu-protein expression. In 39/53 (73%) patients immunohistochemicaland ELISA data showed corresponding results. In 27/30 (90%)patients, from whom sera and tissue could be obtained at thesame time at primary mastectomy, results of immunohistochemistryin primary tumor and serum ELISA were negative and mutuallyconfirmatory. However, the other three patients were positivefor immunohistochemical neu-protein expression in primary tumorbut negative for serum-neu-protein expression. CONCLUSIONS:: Our results suggest that patients with advanced breast cancerand an elevated serum-neu-protein level may have a poor clinicaloutcome. This test might be a useful tool for monitoring patientswith advanced breast carcinoma, but not those with early disease.Further prospective studies are warranted to elucidate the questionof whether this test can contribute to determining prognosisand treatment strategies. breast carcinoma, c-erb-B2, HER-2, neu, oncogene, pl85  相似文献   
7.
Background: Percutaneous cricothyroidotomy is a lifesaving procedure for airway obstruction in trauma victims who need airway establishment and cannot be intubated or in whom intubation has failed.

Methods: The purpose of this study was to examine whether there is a training effect using Seldinger technique emergency cricothyroidotomy (group 1; Arndt Emergency Cricothyroidotomy Catheter Set; Cook Critical Care, Bloomington, IN) versus standard surgical cricothyroidotomy (group 2). Twenty emergency physicians performed five cricothyroidotomies with each method in a total of 200 human cadavers, comparing efficacy and safety (speed, success rate, and injuries).

Results: Seven attempts in group 1 and six in group 2 had to be aborted. Time intervals from the start of the procedure to location of the cricothyroid membrane were not significantly different between the groups. However, time to tracheal puncture (P < 0.01) and time to first ventilation (P < 0.001) were significantly longer in group 2. No time effect could be observed in both groups. The airway was accurately placed into the trachea through the cricothyroid membrane in 88.2% (82 of 93) of the cadavers in group 1 and in 84.0% (79 of 94) in group 2 (not significant). No injuries were observed in group 1, whereas there were six punctures of the thyroid vessels in group 2 (P < 0.05).  相似文献   

8.
The activity of stereoisomeric [1,2-bis(3-hydroxyphenyl)ethylenediamine] dichloroplatinum(II)-complexes (1-PtCl2,R,S; 2-PtCl2, R,R/S,S; 3-PtCl2, R,R; 4-PtCl2, S,S) on several tumor models (MDA-MB 231 breast cancer cell line; P 388 leukemia, mouse; L 1210 leukemia, mouse; L 5222 leukemia, rat; Ehrlich ascites tumor, mouse--wildtype; cisplatin-, etoposide-, cyclophosphamide-, and daunomycin-resistant, resp.) is described. For comparison the analogous [1,2-bis(4-hydroxyphenyl)ethylendiamine]dichloroplatinum (II)-complexes (5-PtCl2, R, S; 6-PtCl2, R,R/S,S; 7-PtCl2, R,R; 8-PtCl2, S,S) and cisplatin are used. 1-PtCl2 to 4-PtCl2 (OH in 3,3'-positions) show their maximum antitumor effect at lower doses than 5-PtCl2 to 8-PtCl2 (OH in 4,4'-positions). 2-PtCl2 and 6-PtCl2 (R,R/S,S) are more active than 1-PtCl2 and 5-PtCl2 (R,S). 4-PtCl2 and 8-PtCl2 (S,S) are superior to 3-PtCl2 and 7-PtCl2 (R,R). On the L 5222 leukemia 2-PtCl2 (R,R/S,S), 4-PtCl2 (S,S) and 8-PtCl2 (S,S) markedly surpass cisplatin. Strong effects are produced by 2-PtCl2 to 4-PtCl2 on the Ehrlich ascites tumor (wildtype, cisplatin-, etoposide-, cyclophosphamide-, and daunomycin-resistant, resp.). The combination of 4-PtCl2 with cisplatin results in a weakly synergistic effect.  相似文献   
9.
OBJECTIVE: Induced hypothermia has been shown to be protective during cardiac surgery, but also in traumatic, ischemic, burn, and neurological injury. In previous in vivo animal experiments, we documented increased leukocyte/endothelial (L/E) cell interaction following normothermic extracorporeal blood circulation (ECC). This study was carried out to investigate whether reduced core temperature during ECC affects the damage to the microcirculation as evidenced by leukocyte adherence and edema formation. METHODS: Intravital fluorescence microscopy was used on the dorsal skinfold chamber preparation in Syrian golden hamsters. ECC was introduced via a micro-rollerpump (1 ml/min) and a 60 cm silicon tube (1mm inner diameter) shunted between the carotid artery and the jugular vein after application of 300IE Heparin/kg per body weight. Experiments were performed in chronically instrumented, awake animals (age 10-14 weeks, weight 65-75 g). Animals of the experimental group were cooled to 18 degrees C body temperature while ECC, followed by a rewarming period (n=7), controls experienced ECC under normothermia (37 degrees C, n=7). RESULTS: 30 min ECC at 18 degrees C resulted in a decrease of rolling and adherent leucocytes (stickers) in postcapillary venules after 1, 4 and 8h compared with the control group (119+/-46 vs. 274+/-113 n/mm2, P<0.05, mean+/-SD; n=7 in each group). Functional capillary density was significantly reduced during hypothermia (80+/-16 vs. 148+/-16 cm/cm2, P<0.05), but restored after rewarming. In contrast, edema formation was markedly increased during hypothermia. CONCLUSIONS: Hypothermia during ECC significantly reduced L/E cell interaction in the early post-ECC period. Hypothermia markedly reduced microvascular perfusion, but was completely restored upon rewarming. Despite a reduced number of adherent leukocytes, no protection of endothelial barrier function was seen as a consequence of induced hypothermia.  相似文献   
10.
Abstract: The efficacy and safety of recombinant human erythropoietin (rhEPO) were tested when given subcutaneously (s.c.) in an escalating dose of 2000–10,000 units (U) daily in 60 patients with cancer-related anaemia (CRA). A positive response, defined as an increase in haemoglobin more than 2 g/dl and independence of blood transfusions, was observed in 23 of 48 evaluable patients (48%) within a median of 8 wk. In detail, rhEPO corrected anaemia in 11 of 14 patients (79%) with malignant lymphoma, in 8 of 15 patients (53%) with multiple myeloma and in 4 of 10 patients (40%) with a solid tumour. The median dose of rhEPO in successful cases was 5000 U daily. Four patients with agnogenic myeloid metaplasia and 5 with myelodysplastic disorder failed to respond to rhEPO. No patient had any severe side effects. Pretreatment serum erythropoietin levels appeared to be a weak predictor for response to rhEPO treatment. In conclusion, rhEPO seems to be safe and effective in correcting CRA in certain groups of patients.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号