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   177970篇
  免费   10398篇
  国内免费   442篇
耳鼻咽喉   2305篇
儿科学   5802篇
妇产科学   3738篇
基础医学   24213篇
口腔科学   7791篇
临床医学   13209篇
内科学   39720篇
皮肤病学   4467篇
神经病学   14872篇
特种医学   5505篇
外国民族医学   26篇
外科学   22283篇
综合类   1500篇
现状与发展   1篇
一般理论   66篇
预防医学   18366篇
眼科学   3257篇
药学   10782篇
中国医学   703篇
肿瘤学   10204篇
  2023年   974篇
  2022年   2067篇
  2021年   3904篇
  2020年   2575篇
  2019年   3629篇
  2018年   5074篇
  2017年   3788篇
  2016年   3551篇
  2015年   4124篇
  2014年   5666篇
  2013年   7118篇
  2012年   11097篇
  2011年   11568篇
  2010年   5853篇
  2009年   5269篇
  2008年   8918篇
  2007年   9526篇
  2006年   8822篇
  2005年   9128篇
  2004年   8565篇
  2003年   7850篇
  2002年   5881篇
  2001年   5166篇
  2000年   5139篇
  1999年   4509篇
  1998年   1621篇
  1997年   1336篇
  1996年   1328篇
  1995年   1122篇
  1994年   1120篇
  1993年   1025篇
  1992年   2769篇
  1991年   2679篇
  1990年   2443篇
  1989年   2451篇
  1988年   2202篇
  1987年   2056篇
  1986年   1911篇
  1985年   1838篇
  1984年   1314篇
  1983年   1060篇
  1982年   595篇
  1981年   542篇
  1980年   534篇
  1979年   981篇
  1978年   645篇
  1977年   501篇
  1975年   564篇
  1974年   593篇
  1973年   579篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Objective: To study the pharmacodynamic and pharmacokinetic properties of oral and intravenous methylergometrine upon uterine motility during menstruation. Study-design: Intra-uterine pressure was measured in six volunteers with a fluid-filled sponge-tipped catheter during menstruation. Methylergometrine was given orally (0.5 mg) or intravenously (0.2 mg) in a cross-over design. Results: After intravenous administration, a fast increase of the frequency of uterine contractions and basal tone occurred with a decrease of amplitude, lasting at least 30 min. Oral administration had a late and less marked effect on uterine motility. An intravenous dose administered 24 h after an oral dose had no effect on uterine motility. Pharmacokinetic data, such as the maximum plasma concentration (Cmax), the time at which Cmax is reached (tmax) and the half-life of absorption (t1/2abs) also demonstrated large individual variations after oral administration. Conclusion: Oral administration of methylergometrine had an unpredictable and late effect on uterine motility on the menstruating uterus, probably due to an unpredictable bioavailability, in contrast with the fast and predictable effect after intravenous administration.  相似文献   
103.
A total of 186 blood samples from 24 HIV-1 seropositive hemophiliac patients, monitored every four months for 29 months, were investigated for the presence of viral antigen in plasma. In addition, peripheral blood mononuclear cells (PBMC) were cultured for HIV-1, using normal PBMC as a target for replication. Antigenemia was detected in 51 % of the patients and from PBMC in 87.5 % of the patients. The incidence of HIV isolation in asymptomatic patients (42.8 %) was similar to that found in symptomatic patients (51.4 %). Patients with opportunistic infections had a higher incidence of lymphocytic viremia (p<0.05). Plasma viremia was closely associated (p<0.05) with low CD4+ counts and infection progression. The persistence of antigenemia was also a marker of a poor clinical course. In treated patients, plasma viremia was the marker that better correlated with the clinical course, and it did not appear during the first nine months of therapy. Zidovudine doses of >500 mg/day significantly lowered the appearance of antigenemia and lymphocytic viremia (p<0.05).  相似文献   
104.
105.
C F Heyns  M L de Kock  C J Deale 《Urology》1990,35(3):247-249
A fifteen-month-old boy with ambiguous external genitalia was found to have a 46XX karyotype, an ovotestis in the right labioscrotal fold, and an absent left gonad. He also had a rudimentary uterus and fallopian tubes and a blind-ending vagina lined with squamous epithelium. These features are compared with those more commonly found in true hermaphroditism.  相似文献   
106.
Transoesophageal echocardiography is a safe and rapid means of obtaining anatomical and dynamic information about the descending aorta. It was used to confirm a suspected diagnosis of ruptured descending aorta.  相似文献   
107.
Percutaneous nephrolithotomy (PCN) enables the urologist to remove upper urinary tract stones through a percutaneous nephrostomy tract. The principal advantages of PCN are the low morbidity, shortened hospital stay and rapid recovery. Percutaneous puncture failed in 5 (11%) of the first 44 patients with upper tract urolithiasis treated by PCN at Tygerberg Hospital. In 35 patients (80%) PCN cleared the kidney of stones but in 4 patients (9%) all stone fragments were not removed during the procedure. If the puncture and dilatation was successful, then 90% of patients were stone-free after PCN. Complications were minimal except for a diabetic who died of septicaemia. PCN is an alternative to open renal surgery in the management of most upper urinary tract stones. The technique is readily mastered by any urologist experienced in endoscopic surgery.  相似文献   
108.
BACKGROUND: In general practice, acute sinusitis is frequently diagnosed and treated with antibiotics. OBJECTIVE: This study aimed to determine the evidence for the effectiveness of antibiotic treatment in acute maxillary sinusitis in adults by assessing the methodological quality of placebo-controlled double-blind randomized trials. METHOD: An evaluation by four raters through a 35-item scoring-scale for internal and external validity of all placebo-controlled double-blind randomized trials on acute sinusitis found between January 1966 and July 1996. RESULTS: Eighty-five trials were excluded because they were not placebo-controlled, double-blind, randomized, or were carried out in patients with chronic sinusitis or in children. The three remaining trials were performed in different populations (one in general practice) between 1973 and 1978. Only one study claimed superiority of antibiotic treatment. Different inclusion criteria and major outcome measures were used by the authors. The reliability of major outcome events was reported poorly or not at all and in two studies outcome measures were clinically inappropriate. The studies scored 30-62% of the maximum attainable score for internal validity and 10-20% for external validity. CONCLUSION: The effectiveness of antibiotic treatment in acute maxillary sinusitis in a general practice population is not based sufficiently on evidence.   相似文献   
109.
Neutrophil oxidative metabolism, C3d and beta 2 microglobulin levels, were assessed in nine consecutive patients undergoing cardiopulmonary bypass surgery with polypropylene hollow fiber oxygenators for open cardiac operations. Generation of oxygen free radicals by neutrophils was measured as luminol-enhanced chemiluminescence after stimulation with opsonized Zymosan and phorbol myristate acetate. A significant increase in light emission was detected by using both of the chemiluminescence stimulators. Moreover, a remarkable and significant increase in C3d levels was found already at 10 min. Conversely minimal changes in levels of beta 2 microglobulin were detected during cardiopulmonary bypass surgery. These data suggest that the impact of the patient blood with the foreign surface of cardiopulmonary bypass results in activation of phagocyte cells with increased potential in oxygen consumption. These effects could be partially complement-mediated.  相似文献   
110.
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