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   7249篇
  免费   406篇
  国内免费   39篇
耳鼻咽喉   79篇
儿科学   258篇
妇产科学   80篇
基础医学   1241篇
口腔科学   125篇
临床医学   552篇
内科学   1731篇
皮肤病学   193篇
神经病学   757篇
特种医学   256篇
外科学   607篇
综合类   50篇
预防医学   392篇
眼科学   161篇
药学   562篇
中国医学   12篇
肿瘤学   638篇
  2024年   8篇
  2023年   76篇
  2022年   121篇
  2021年   171篇
  2020年   101篇
  2019年   150篇
  2018年   189篇
  2017年   153篇
  2016年   157篇
  2015年   131篇
  2014年   233篇
  2013年   313篇
  2012年   493篇
  2011年   492篇
  2010年   277篇
  2009年   304篇
  2008年   465篇
  2007年   541篇
  2006年   481篇
  2005年   515篇
  2004年   513篇
  2003年   477篇
  2002年   477篇
  2001年   59篇
  2000年   37篇
  1999年   62篇
  1998年   89篇
  1997年   82篇
  1996年   70篇
  1995年   62篇
  1994年   40篇
  1993年   61篇
  1992年   45篇
  1991年   36篇
  1990年   29篇
  1989年   24篇
  1988年   22篇
  1987年   16篇
  1986年   9篇
  1985年   10篇
  1984年   15篇
  1983年   13篇
  1982年   13篇
  1981年   7篇
  1980年   13篇
  1979年   7篇
  1977年   5篇
  1975年   5篇
  1973年   5篇
  1966年   3篇
排序方式: 共有7694条查询结果,搜索用时 15 毫秒
51.
52.
To determine the role of percutaneous vertebroplasty (PVP) in bone formation and the union of vertebral pseudarthrosis, we analyzed 14 patients with an average follow-up duration of 21 months. Evaluation methods included back pain (visual analog scale: VAS), wedge angle, dynamic mobility, radiographic remodeling including callus and spur formation, and union status. The Student's t test was used for statistical analysis and a probability of less than 0.05 was determined as a significant difference. Back pain improved in all 14 patients with a VAS score of 57.8 ± 23.5 mm (average ± standard deviation) preoperatively and 14.7 ± 16.4 mm at the final follow-up (P < 0.001). The wedge angle decreased from 21.6° ± 8.3° (average ± standard deviation) preoperatively to 13.2° ± 6.9° at the final follow-up (P < 0.001). Callus formation was seen in four patients. Bony spurs were seen in the affected vertebra in preoperative radiographs in all patients, and were further developed to a solidified form during follow up after PVP. Dynamic mobility of the affected vertebrae was 6.9 ± 2.9 mm preoperatively, which decreased to 1.1° ± 0.7° at the final follow-up (P < 0.001). Notably, all patients showed the dynamic vertebral mobility of 2 mm or less. Nevertheless, only two patients exhibited the dynamic vertebral mobility of 0 mm at the final follow-up, which is referred to as bone union. These findings indicate that PVP serves as a mechanical stabilizer for vertebral pseudarthrosis, which leads to immediate pain relief and segmental bony responses.  相似文献   
53.
We present a case of prolonged hoarseness after tracheal intubation in a 62-year-old woman with bronchial asthma who underwent a pylorogastrectomy under a combination of epidural and general anesthesia. After the induction of anesthesia, the patient was carefully intubated using a 7.5-mm cuffed endotracheal tube without a stylet to avoid causing an asthma attack; the patient was extubated approximately 6 hours after the tracheal intubation. On the first postoperative day, the patient complained of hoarseness, vocal fatigue, and dysphagia. A direct laryngoscopy performed by an otorhinolaryngologist revealed dyskinesia of the left vocal cord and sufficient arytenoid cartilage mobility. The poor vocal fold mobility was probably caused by the force exerted on the left arytenoid by the convex curvature of the endotracheal tube, which had been inserted from the right side of the mouth, or a backward pressure on the thyroid cartilage during intubation. Early treatment is crucial in such cases, since the cricoarytenoid joint can become fibrosed in an unfavorable position. Fortunately, all the symptoms disappeared after one month in the present case. Although the trigger responsible for the spontaneous healing remains unknown, natural recovery might be associated with proper use of the vocal cords.  相似文献   
54.
Recently we have reported cases of demyelinating inflammatory neuropathy showing elevated titers of anti-GD3 antibodies, which occurs rarely in Guillain-Barré syndrome. To examine the correlation between the anti-GD3 antibody titer and Campylobacter jejuni infection, we sensitized female Lewis rats with lipopolysaccharides (LPSs) from serotype HS19 of C. jejuni and examined changes in nerve conduction velocity and nerve conduction block (P/D ratio). After 16 weeks of sensitization, animals revealed decreases of nerve conduction velocity and conduction block (P/D ratio) and high titer of anti-GD3 antibodies. These anti-GD3 antibodies also blocked transmission in neuromuscular junctions of spinal cord-muscle cells cocultures. The GD3 epitope was verified to be located on the Schwann cell surface and nodes of Ranvier in rat sciatic nerve. To determine the target epitope for GD3 antibodies in causing nerve dysfunction, the LPS fraction containing the GD3 epitope was purified from the total LPS by using an anti-GD3 monoclonal antibody-immobilized affinity column. Subsequently, chemical analysis of the oligosaccharide portion was performed and confirmed the presence of a GD3-like epitope as having the following tetrasaccharide structure: NeuAcalpha2-8NeuAc2-3Galbeta1-4Hep. Our data thus support the possibility of a contribution of GD3 mimicry as a potential pathogenic mechanism of peripheral nerve dysfunction.  相似文献   
55.
Astrocytes have essential roles for neuron survival and function, so that their demise in neurodegenerative insults, such as ischemia, deserves attention. A major event of the cell death cascade in ischemia is the reversed operation of excitatory amino acid transporters (EAAT), releasing glutamate. Cytotoxicity is conventionally attributed to extracellular glutamate accumulation. We previously reported that mimicking such dysfunction by EAAT substrate inhibitors, whose uptake induces glutamate release by heteroexchange, triggers glutathione (GSH) depletion and oxidative death of differentiated astrocytes in culture. Here we demonstrate that astrocyte death, although correlated with glutamate release, is not resulting from high extracellular glutamate-mediated toxicity. L-glutamate per se was gliotoxic only at concentrations much higher than the maximum reached with the potent EAAT substrate inhibitor L-trans-pyrrolidine-2,4-dicarboxylate (PDC), and toxicity was lower. Moreover, high glutamate concentrations offered protection against PDC. Protection was also provided by L-aspartate, which is both transported by EAAT and metabolized into glutamate, and by inhibiting glutamine synthetase, which uses transported glutamate to synthesize glutamine. Neither D-aspartate, a metabolically inert EAAT substrate, nor compounds that can provide glutamate intracellularly but are not EAAT substrates offered protection. Interestingly, only the compounds providing protection prevented PDC-induced GSH depletion. These data strongly suggest that reversed uptake-mediated astrocyte death results from the leakage of glutamate from a compartmentalized intracellular metabolic pool specifically fuelled by EAAT, crucial for preserving GSH contents. In addition, we provide evidence for a minor contribution of the cystine-glutamate antiporter x(c) (-) but a major role of the 5-lipoxygenase pathway in this death mechanism.  相似文献   
56.
BACKGROUND: Although membranous nephropathy is a common cause of nephrotic syndrome in adults, its treatment remains under debate. METHODS: To clarify the effects of steroid therapy, the data of 51 Japanese adult patients with idiopathic membranous nephropathy who received treatment at our department were analyzed retrospectively. We divided the patients with nephrotic syndrome and a serum creatinine level <1.7 mg/dL, into two groups: the steroid therapy group (n=20) and the non-steroid therapy group (n=7), and compared the clinical characteristics between the two groups. RESULTS: Significantly decreased proteinuria levels (p<0.05) after 2 and 5 years were observed in the steroid therapy group as compared to the non-steroid therapy group. There was no significant difference in the serum creatinine levels after 2 and 5 years between the steroid therapy group and the non-steroid therapy group. CONCLUSION: Steroid therapy in idiopathic membranous nephropathy showed good efficacy in patients with nephrotic syndrome.  相似文献   
57.
BACKGROUND: The incidence of herpes zoster increases with age. Immediate pain relief is required for prevention of postherpetic neuralgia (PHN) and also its related symptoms that worsen the general condition because acute herpetic pain often interferes with sleep, mood, and general activities in elderly patients. Nerve block is useful to relief acute pain and recommended for prevention of PHN. Tricyclic antidepressant drugs have antinoticeptive effect in acute pain in experimental models, in addition to its antidepressant effect. METHODS: Forty elderly patients with herpes zoster within 3 months after the onset underwent nerve blocks and received tricyclic antidepressant drugs. We assessed the effect of treatments and adverse effects. RESULTS: No significant adverse effects were found in elderly patients who had received nerve blocks and/or tricyclic antidepressant drugs. Alleviation of acute pain was obtained in more than 80% of patients, and in all patients depressive state and/or disturbance of the general condition were significantly improved. CONCLUSIONS: With careful technique and assessment of patients, both nerve block and tricyclic antidepressant drugs were beneficial and safe treatments in elderly patients with herpes zoster.  相似文献   
58.
PURPOSE: To investigate neuromuscular block using accelography after administration of vecuronium under sevoflurane 8% induction and maintenance with sevoflurane 2% in adults. METHODS: Patients were allocated to three groups: (1) group I: anesthesia was induced and maintained with propofol and fentanyl (n= 15), (2) group II: anesthesia was induced with propofol and maintained with N2O(66%)-O2-sevoflurane 2% (n = 15), (3) group III: anesthesia was induced with sevoflurane 8% using a vital capacity inhalation induction and maintained with N2O(66%)-O2-sevoflurane 2% (n = 15). 0.1 mg x kg(-1) vecuronium was used for paralysis three minutes after anesthetic induction and reversed using intravenous 0.04 mg x kg(-1) neostigmine with 0.02 mg kg atropine when the train-of-four (TOF) ratio returned to 25%. RESULTS: The onset time from initial administration of vecuronium to maximal block in the group III was shorter than that in the groups I and II (139 +/- 35, 193 +/- 35 and 188 +/- 47s, respectively: P < 0.05). The clinical duration from maximal block to 25% recovery of TOF ratio in group II and III was longer than that in the group I (47 +/- 15, 48 +/- 14 and 36 +/- 10 min, respectively: P < 0.05). The reversal times from administration of neostigmine to 75% of TOF ratio in groups II and III were longer than that in the group I (196 +/- 53, 208 +/- 64 and 136 +/- 28s, respectively: P < 0.05). CONCLUSIONS: Vital capacity inhalation induction of anesthesia with sevoflurane accelerates onset and prolongs duration of vecuronium neuromuscular block compared with propofol-fentanyl anesthesia.  相似文献   
59.
BACKGROUND: In our institution, spinal anesthesia is the first choice for cesarean section. After the introduction of bupivacaine in 2000 in Japan, the intrathecal anesthetic agent shifted from tetracaine to bupivacaine. We analyzed the anesthesia for cesarean section in recent 7 years and compared the anesthetic quality of tetracaine with that of bupivacaine. METHODS: The anesthetic records were reviewed in the patients who had received cesarean section between January 1998 and December 2004 at our institution. RESULTS:There were 10456 deliveries during the study period with a cesarean section rate of 28.2% (2947 cases). Ninety-one percent of cesarean section was performed under spinal anesthesia. Spinal anesthetic agent shifted from tetracaine to bupivacaine in 2000-2001, both of which was prepared as a hyperbaric solution and supplemented with 0.1 mg of morphine hydrocloride. Of the 2711 patients in whom a cesarean section was started under spinal anesthesia, 20 (0.7%) required conversion to general anesthesia. Three hundred eighteen patients (11.7%) required some analgesic supplementation. The incidence of intra-operative analgesic supplementation was greater in the patients anesthetized with hyperbaric tetracaine and morphine than in those anesthetized with hyperbaric bupivacaine and morphine (22.96% vs 4.20% ; P<0.01). The conversion rate from spinal to general anesthesia for cesarean section was 0.7%. CONCLUSIONS: Comparing these two intrathecal anesthetic agents, the rate of analgesic supplementation in those anesthetized with bupivacaine was lower than in those anesthetized with tetracaine. This suggests that bupivacaine provides the more profound blockade of the visceral pain than tetracaine, and is superior as a local anesthetic.  相似文献   
60.

Background

For almost 30 years, transanal endoscopic microsurgery (TEM) has been the mainstay treatment for large rectal lesions. With the advent of endoscopic submucosal dissection (ESD), flexible endoscopy has aimed at en bloc R0 resection of superficial lesions of the digestive tract. This systematic review and meta-analysis compared the safety and effectiveness of ESD and full-thickness rectal wall excision by TEM in the treatment of large nonpedunculated rectal lesions preoperatively assessed as noninvasive.

Methods

A systematic review of the literature published between 1984 and 2010 was conducted (Registration no. CRD42012001882). Data were integrated with those from the original databases requested from the study authors when needed. Pooled estimates of the proportions of patients with en bloc R0 resection, complications, recurrence, and need for further treatment in the ESD and TEM series were compared using random-effects single-arm meta-analysis.

Results

This review included 11 ESD and 10 TEM series (2,077 patients). The en bloc resection rate was 87.8 % (95 % confidence interval [CI] 84.3–90.6) for the ESD patients versus 98.7 % (95 % CI 97.4–99.3 %) for the TEM patients (P < 0.001). The R0 resection rate was 74.6 % (95 % CI 70.4–78.4 %) for the ESD patients versus 88.5 % (95 % CI 85.9–90.6 %) for the TEM patients (P < 0.001). The postoperative complications rate was 8.0 % (95 %, CI 5.4–11.8 %) for the ESD patients versus 8.4 % (95 % CI 5.2–13.4 %) for the TEM patients (P = 0.874). The recurrence rate was 2.6 % (95 % CI 1.3–5.2 %) for the ESD patients versus 5.2 % (95 % CI 4.0–6.9 %) for the TEM patients (P < 0.001). Nevertheless, the rate for the overall need of further abdominal treatment, defined as any type of surgery performed through an abdominal access, including both complications and pathology indications, was 8.4 % (95 % CI 4.9–13.9 %) for the ESD patients versus 1.8 % (95 % CI 0.8–3.7 %) for the TEM patients (P < 0.001).

Conclusions

The ESD procedure appears to be a safe technique, but TEM achieves a higher R0 resection rate when performed in full-thickness fashion, significantly reducing the need for further abdominal treatment.  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