全文获取类型
收费全文 | 8949篇 |
免费 | 610篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 143篇 |
儿科学 | 229篇 |
妇产科学 | 200篇 |
基础医学 | 1195篇 |
口腔科学 | 543篇 |
临床医学 | 787篇 |
内科学 | 1794篇 |
皮肤病学 | 102篇 |
神经病学 | 998篇 |
特种医学 | 290篇 |
外科学 | 1337篇 |
综合类 | 78篇 |
预防医学 | 826篇 |
眼科学 | 104篇 |
药学 | 553篇 |
中国医学 | 56篇 |
肿瘤学 | 343篇 |
出版年
2023年 | 58篇 |
2022年 | 134篇 |
2021年 | 237篇 |
2020年 | 149篇 |
2019年 | 234篇 |
2018年 | 254篇 |
2017年 | 161篇 |
2016年 | 189篇 |
2015年 | 243篇 |
2014年 | 312篇 |
2013年 | 342篇 |
2012年 | 532篇 |
2011年 | 625篇 |
2010年 | 314篇 |
2009年 | 284篇 |
2008年 | 470篇 |
2007年 | 432篇 |
2006年 | 414篇 |
2005年 | 394篇 |
2004年 | 333篇 |
2003年 | 311篇 |
2002年 | 301篇 |
2001年 | 243篇 |
2000年 | 255篇 |
1999年 | 191篇 |
1998年 | 89篇 |
1997年 | 78篇 |
1996年 | 60篇 |
1995年 | 48篇 |
1994年 | 49篇 |
1993年 | 36篇 |
1992年 | 157篇 |
1991年 | 128篇 |
1990年 | 125篇 |
1989年 | 120篇 |
1988年 | 131篇 |
1987年 | 130篇 |
1986年 | 91篇 |
1985年 | 93篇 |
1984年 | 73篇 |
1983年 | 63篇 |
1982年 | 41篇 |
1981年 | 36篇 |
1979年 | 64篇 |
1978年 | 34篇 |
1975年 | 41篇 |
1974年 | 45篇 |
1973年 | 50篇 |
1971年 | 48篇 |
1970年 | 33篇 |
排序方式: 共有9578条查询结果,搜索用时 0 毫秒
991.
Caspase-3 is a pivotal mediator of apoptosis during regression of the ovarian corpus luteum 总被引:5,自引:0,他引:5
Carambula SF Matikainen T Lynch MP Flavell RA Gonçalves PB Tilly JL Rueda BR 《Endocrinology》2002,143(4):1495-1501
Because caspase-3 is considered a primary executioner of apoptosis and has been implicated as a mediator of luteal regression, we hypothesized that corpora lutea (CL) derived from caspase-3 null mice would exhibit a delayed onset of apoptosis during luteal regression, when compared with CL derived from wild-type (WT) mice. To test this hypothesis, ovulation was synchronized in immature (postpartum d 24-27) WT and caspase-3-deficient female littermates by exogenous gonadotropins. Individual CL were isolated by manual dissection, 30 h after ovulation, and placed in organ culture dishes in the absence of serum and growth factors. At the time of isolation (0 h) and after 24, 48, and 72 h in culture, the CL were removed and assessed for the presence of processed (active) caspase-3 enzyme and for apoptosis by multiple criteria. There was no evidence of active caspase-3 enzyme or apoptosis in either WT or caspase-3-deficient CL before culture. However, CL derived from the WT mice exhibited a time-dependent increase in the level of active caspase-3 and apoptosis during culture. By comparison, CL derived from caspase-3-deficient mice, cultured in parallel, failed to exhibit any detectable active caspase-3 and showed attenuated rates of apoptosis. To extend these findings derived from ex vivo culture experiments, ovaries were collected from WT and caspase-3 null female littermates at 2, 4, or 6 d post ovulation, and the occurrence of apoptosis within the CL was analyzed. Whereas ovaries of WT mice had only residual luteal tissue at d 6 post ovulation, ovaries collected from caspase-3-deficient mice retained many CL, at d 6 post ovulation, that were similar in size to those observed in the early luteal phase of WT mice. Importantly, there was no dramatic increase in apoptosis in CL of caspase-3-deficient mice at any time point examined post ovulation, indicating that the involution process had indeed been delayed. In contrast, the levels of progesterone declined regardless of genotype. These data provide the first direct evidence that caspase-3 is functionally required for apoptosis to proceed normally during luteal regression. However, caspase-3 is not a direct mediator of the decrease in steroidogenesis associated with luteolysis. 相似文献
992.
Thymic size and lymphocyte restoration in patients with human immunodeficiency virus infection after 48 weeks of zidovudine, lamivudine, and ritonavir therapy 总被引:13,自引:0,他引:13
Smith KY Valdez H Landay A Spritzler J Kessler HA Connick E Kuritzkes D Gross B Francis I McCune JM Lederman MM 《The Journal of infectious diseases》2000,181(1):141-147
Human immunodeficiency virus (HIV) infection is associated with progressive loss of circulating CD4+ lymphocytes. Treatment with highly active antiretroviral therapy (HAART) has led to increases in CD4+ T lymphocytes of naive (CD45RA+62L+) and memory (CD45R0+RA-) phenotypes. Thymic computerized tomography scans were obtained on 30 individuals with HIV disease to investigate the role of the thymus in cellular restoration after 48 weeks of HAART. Individuals with abundant thymic tissue had higher naive CD4+ T lymphocyte counts at weeks 2-24 after therapy than individuals with minimal thymic tissue. Individuals with abundant thymic tissue had significantly larger increases in naive CD4+ cells during the first 4 weeks of therapy. These individuals were also more likely to experience viral rebound despite comparable initial declines in plasma HIV-1 RNA. These findings suggest that there is a complex relationship among the thymus, viral replication, and lymphocyte restoration after application of HAART in HIV disease. 相似文献
993.
Kessler CM 《Current opinion in hematology》2000,7(6):408-413
The treatment of alloantibody and autoantibody inhibitors directed against the factor VIII coagulant protein is one of the most challenging and expensive problems in hematology. Because the currently available plasma replacement products used in this context do not control the bleeding complications in all patients, and because of the usual emergent quality of the bleeding complications, there has been a definite need to have a uniformly reliable product for instant use, which possesses a high degree of hemostatic reliability and safety. The recent introduction of recombinant factor VIIa (rFVIIa) has been a welcome addition to the pharmacologic armamentarium for the treatment of neutralizing antibodies against coagulation factors. The mechanisms of action of rFVIIa have also been interesting and have provided insight into how the coagulation pathway accomplishes adequate hemostasis. This review will discuss this new medication and place into the context of coagulation inhibitor therapy. 相似文献
994.
N Winqvist A Nauclér V Gomes I Djamanca T Koivula H Jensen F Dias G Biberfeld G K?llenius R Norberg 《The international journal of tuberculosis and lung disease》2000,4(9):845-852
SETTING: Raoul Follereau Hospital, Bissau, Guinea-Bissau. OBJECTIVE: To study the long-term outcome of patients with bacteriologically verified tuberculosis (TB), with or without human immunodeficiency virus (HIV) co-infection. DESIGN: Sputum samples were collected from all patients referred to the hospital with clinical symptoms of pulmonary tuberculosis. Direct microscopy and culture was performed at the Health Laboratory. Patients with a culture positive for Mycobacterium tuberculosis were followed for 3 years, and underlying factors were analysed regarding the outcome of treatment. A group of sex and age-matched HIV-negative individuals was used as controls. RESULTS: Of 206 bacteriologically verified pulmonary TB patients, 168 were followed up. Antibodies to HIV-2 were found in 33 patients (19.6%); eight patients (4.8%) had antibodies to HIV-1 or showed dual reactivity. Of 149 patients discharged to follow ambulatory treatment, the survival rate of HIV-2-positive patients was 42.3% (11/26) and for HIV-negative patients it was 81.9% (95/116). The difference in survival between HIV-2-positive and HIV-negative patients was highly significant (P < 0.00001). HIV-negative TB patients had a significantly higher mortality than their controls (mortality ratio 3.75, 95% confidence interval 1.58-8.90). Most patients who survived, regardless of HIV status, also became free from symptoms compatible wtih pulmonary TB. CONCLUSION: Although the mortality rate among HIV-positive TB patients was very much higher than among HIV-negative patients, there are weighty arguments for active contact tracing and effective treatment of all TB patients. 相似文献
995.
Regional cerebral activation in irritable bowel syndrome and control subjects with painful and nonpainful rectal distention 总被引:38,自引:0,他引:38
BACKGROUND & AIMS: Irritable bowel syndrome (IBS) is characterized by visceral hypersensitivity, possibly related to abnormal brain-gut communication. Positron emission tomography imaging has suggested specific central nervous system (CNS) abnormalities in visceral pain processing in IBS. This study aimed to determine (1) if functional magnetic resonance imaging (fMRI) detects CNS activity during painful and nonpainful visceral stimulation; and (2) if CNS pain centers in IBS respond abnormally. METHODS: fMRI was performed during nonpainful and painful rectal distention in 18 patients with IBS and 16 controls. RESULTS: Rectal stimulation increased the activity of anterior cingulate (33/34), prefrontal (32/34), insular cortices (33/34), and thalamus (32/34) in most subjects. In IBS subjects, but not controls, pain led to greater activation of the anterior cingulate cortex (ACC) than did nonpainful stimuli. IBS patients had a greater number of pixels activated in the ACC and reported greater intensity of pain at 55-mm Hg distention than controls. CONCLUSIONS: IBS patients activate the ACC, a critical CNS pain center, to a greater extent than controls in response to a painful rectal stimulus. Contrary to previous reports, these data suggest heightened pain sensitivity of the brain-gut axis in IBS, with a normal pattern of activation. 相似文献
996.
Havlir DV Tierney C Friedland GH Pollard RB Smeaton L Sommadossi JP Fox L Kessler H Fife KH Richman DD 《The Journal of infectious diseases》2000,182(1):321-325
Human immunodeficiency virus (HIV)-infected subjects receiving zidovudine were randomized either to add stavudine (d4T) or didanosine (ddI) to their current regimen or to switch to ddI or d4T monotherapy. After 16 weeks of therapy, the mean reduction in HIV RNA from baseline was 0.14 log(10) copies/mL in patients receiving d4T or zidovudine plus d4T. In subjects receiving ddI or ddI plus zidovudine, reductions were 0.39 and 0.56 log(10), respectively. CD4 cell counts remained stable or showed modest increases in all arms except the zidovudine plus d4T arm. Patients receiving zidovudine plus d4T showed progressive declines in CD4 cell counts with a median of 22 cells/mm(3) below baseline by 16 weeks. Examination of intracellular levels of d4T-triphosphate in 6 subjects was consistent with previous in vitro studies demonstrating pharmacologic antagonism between zidovudine and d4T. Analysis of these data suggests that zidovudine and d4T should not be prescribed in combination and that ddI provides greater antiviral activity than d4T in zidovudine-treated patients. 相似文献
997.
A diagnosis of heart failure (HF) can be difficult, especially in patients with mild symptomatology. The purpose of this study was to evaluate the significance of brain natriuretic peptide (BNP) in the diagnosis of HF with systolic or isolated diastolic ventricular dysfunction. One hundred patients and 9 controls were included in the study. Eighty-five patients were diagnosed with HF, based on clinical and echocardiographic findings. BNP levels were accurate for the diagnosis of HF, with an area under the receiver operating characteristic (ROC) curve (AUC) of 0.92. In addition, BNP levels showed an excellent accuracy for the diagnosis of isolated diastolic HF (AUC = 0.89). These data suggest that the measurement of BNP levels may be helpful in the diagnosis of HF and in selecting patients for further evaluation. Furthermore, BNP measurement can play an important role in the diagnosis of isolated diastolic HF. 相似文献
998.
Valdez H Smith KY Landay A Connick E Kuritzkes DR Kessler H Fox L Spritzler J Roe J Lederman MB Lederman HM Evans TG Heath-Chiozzi M Lederman MM 《AIDS (London, England)》2000,14(1):11-21
OBJECTIVES: To ascertain if immunization results in the restoration of responses to recall antigens, in the development of responses to presumed neoantigens, and to identify the virologic and immunologic correlates of these responses in persons with HIV-1 infection. DESIGN AND SETTING: Open-label study carried out at three university-affiliated AIDS Clinical Trials Units in the United States. SUBJECTS AND METHODS: Thirty-one subjects participating in AIDS Clinical Trials Group Protocol 375 who had received zidovudine, lamivudine, and ritonavir for at least 48 weeks. Subjects were immunized with tetanus toxoid (TT) at entry and with inactivated hepatitis A vaccine (hep A) and keyhole limpet hemocyanin (KLH) at entry and 6 weeks. The development of antibody, lymphocyte proliferative assay (LPA), and delayed-type hypersensitivity (DTH) responses after immunization were monitored. RESULTS: The LPA and DTH responses to TT improved in 57 and 68% of participants, respectively; 73 and 65% developed enhanced LPA and DTH responses to KLH. Forty-eight percent of patients developed a four-fold increase in antibody concentration to tetanus. Seventy-three percent of patients without detectable hepatitis A antibodies at baseline developed antibodies after immunization. Eighty-three percent of patients experienced at least a four-fold rise in KLH antibody concentration. Immune activation and viral load predicted poor recall responses and the number of memory CD4+ T-cells predicted good responses to recall antigens. Na?ve CD4+ T-cell numbers, decrease in viral load, increases in CD4+ and CD28+ cells, and decreases in immune activation were associated with responses to presumed neoantigens. CONCLUSIONS: Most HIV-infected patients treated with potent combination antiretrovirals develop responses to recall and presumed neoantigens after immunization. Functional immune restoration in response to immunization is related to control of viral replication, decreased immune activation as well as to both quantitative and qualitative restoration of circulating T- lymphocyte subpopulations. 相似文献
999.
Aybek T Dogan S Kessler P Neidhart G Khan MF Wimmer-Greinecker G Moritz A 《Zeitschrift für Kardiologie》2002,91(3):238-242
BACKGROUND: In minimally invasive coronary artery bypass surgery beating heart procedures and operations via limited incisions became more popular and are routinely performed in many centers. An additional approach to minimize general trauma is avoidance of general anesthesia endotracheal intubation. PATIENTS AND METHODS: Between March and June 2001, 14 spontaneously breathing patients underwent coronary artery bypass grafting on the beating heart without general anesthesia. Intra- and postoperative analgesia management was performed using continuous epidural infusion of local anesthetics at level Th2-Th3. Single (n = 8) as well as double (n = 5) and triple (n = 1) bypass grafting was performed with the off pump technique. Surgical access to the chest cavity was created via partial (n = 8) or complete sternotomy (n = 6). RESULTS: Twelve patients remained awake throughout the procedure; 2 patients required secondary intubation due to incomplete sensory block and pneumothorax. Operating time was 94 +/- 18 minutes. Intermediate care monitoring time amounted to 4.8 +/- 0.6 hours. No surgery-related complications or myocardial infarction occurred. Postoperative angiography reviewed good graft function in all patients. CONCLUSION: Our preliminary experience shows that complete surgical revascularization is safe and feasible without endotracheal intubation and general anesthesia. Thus, invasiveness in cardiac surgery is further reduced with less need for intensive care unit monitoring enabling faster mobilization and recovery. 相似文献
1000.