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   392384篇
  免费   25528篇
  国内免费   3871篇
耳鼻咽喉   5249篇
儿科学   8366篇
妇产科学   10199篇
基础医学   54563篇
口腔科学   12070篇
临床医学   31910篇
内科学   80376篇
皮肤病学   8685篇
神经病学   27953篇
特种医学   14392篇
外国民族医学   87篇
外科学   62082篇
综合类   12269篇
现状与发展   5篇
一般理论   65篇
预防医学   18336篇
眼科学   9825篇
药学   32320篇
  2篇
中国医学   2865篇
肿瘤学   30164篇
  2021年   3320篇
  2019年   3207篇
  2018年   5030篇
  2017年   3842篇
  2016年   3931篇
  2015年   4654篇
  2014年   6442篇
  2013年   8013篇
  2012年   10937篇
  2011年   11273篇
  2010年   6881篇
  2009年   6364篇
  2008年   10157篇
  2007年   10955篇
  2006年   10811篇
  2005年   9908篇
  2004年   9282篇
  2003年   8999篇
  2002年   8614篇
  2001年   28569篇
  2000年   29096篇
  1999年   23983篇
  1998年   5419篇
  1997年   4470篇
  1996年   3985篇
  1995年   3641篇
  1994年   3199篇
  1993年   2931篇
  1992年   16153篇
  1991年   14887篇
  1990年   14233篇
  1989年   14014篇
  1988年   12637篇
  1987年   12108篇
  1986年   11151篇
  1985年   10359篇
  1984年   6945篇
  1983年   5605篇
  1982年   2729篇
  1979年   5485篇
  1978年   3352篇
  1977年   2973篇
  1975年   2647篇
  1974年   3070篇
  1973年   2870篇
  1972年   2832篇
  1971年   2773篇
  1970年   2514篇
  1969年   2545篇
  1968年   2250篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
993.
Buserelin, a luteinizing hormone releasing hormone agonist was administered nasally in doses of 900 micrograms daily to inhibit the ovarian cycle. Of 16 patients recruited, ten completed the treatment. Daily symptoms were measured on the Visual Analogue Scale and Trigg's trend analysis utilized for the analysis. The peak severity of symptoms (ESAmax) and the maximum global scores (Gmax) reduced on buserelin treatment. The minimum global scores (Gmin) and the minimum score for each symptom (ESAmin) increased, suggesting worsening of underlying symptoms. The difference between ESAmax and ESAmin (ESAdelta) and Gmax and Gmin (Gdelta) were calculated to determine the degree of symptom change. The delta scores for symptoms of depression, bloatedness and breast symptoms, and Gdelta were significantly reduced (p less than 0.05) on buserelin, whilst the latter significantly worsened in the follow-up months. Side-effects may limit the place of buserelin in the long-term treatment of premenstrual syndrome, although combination of additional hormonal treatment may facilitate long-term treatment.  相似文献   
994.
A case of Plasmodium falciparum malaria is reported in a 25-year-old pregnant woman with a history of three previous cesarean sections. She developed premature precipitate labor which was complicated by stillbirth, uterine rupture, bladder and vaginal tears necessitating hysterectomy.  相似文献   
995.
The generation of monoenergetic or quasimonoenergetic x-ray spectra has been accomplished by several methods including the use of K-edge filtration, characteristic radiation, crystal monochromators, and multilayer mirrors. In this paper some practical questions are discussed regarding the possibility of obtaining narrow-band spectra using x-ray reflection in glass capillary optics which have been reported recently in connection with the focusing and generation of parallel x-ray beams. Derivation of formulas for double and triple reflection with and without additional K-edge filtration imply that these methods are superior to the use of filtration alone. It is shown that the double reflection scheme is most sensitive to the angular divergence of the beam emanating from the capillary array used to generate the incident parallel beam. Simulations using three reflections predict output spectra which are relatively insensitive to blurring due to angular divergence. A small amount of K-edge filtration in combination with three reflections provides considerable sharpening of the x-ray spectrum. Aside from the spectral selectivity provided by the capillary array, the reduced divergence of the primary transmission may have advantages for scatter rejection in situations where the air gap between the patient and detector is increased by an amount consistent with the resolution requirements of the application. In parallel beam situations, the use of capillary arrays between the patient and detector may also be useful for the rejection of divergent scattered radiation.  相似文献   
996.
Eighty-nine consecutive Chinese patients (69 males, 20 females) with acute myocardial infarction treated by 100 mg recombinant tissue-plasminogen activator (rt-PA) (7 intracoronarily, 82 intravenously) at 3.7 +/- 1.0 hours after onset, and intravenous heparin or dipyridamole therapy started at 3 hours, were studied prospectively. Their mean age was 59.6 +/- 10.6 years. Forty-six patients (51.7%) had anterior and 39 patients (43.8%) had inferior infarcts. Clinical evidence of reperfusion was seen in 63 patients (72.8%), while new complications included hypotension (5.6%), heart failure (6.7%), cardiac arrhythmias (76.4%), hematoma around vascular access sites (23.6%), melena (2.2%) and cerebral infarction (2.2%). Maximal changes in coagulation profiles were seen at 3 hours, including a decrease in fibrinogen (by 64.2%), an increase in FDP by 11.7 times and D-dimers by 4.4 times. Nine patients (10.1%) had recurrence of angina and 6 patients (6.9%) died due to pump failure (5) and reinfarction (1). Angiogram at 14 days confirmed TIMI (2 or 3) patency of infarct related arteries in 62/81 (76.5%) patients, with a mean global ejection fraction of 52.5 +/- 12.4%. Nearly all survivors could maintain class I-II functional status after discharge. The safety and promises of rt-PA for acute myocardial infarction in the Chinese were confirmed.
  相似文献   
997.
998.
999.
MICs of temocillin, carbenicillin, ticarcillin, mezlocillin, piperacillin and ampicillin were determined for mutant series of Enterobacter cloacae, Citrobacter freundii, Proteus vulgaris, Morganella morganii and Serratia marcescens with inducible, stably derepressed or basal expression of chromosomal Class I beta-lactamases. Ampicillin was inactive (MIC greater than 256 mg/l) both against beta-lactamase-inducible organisms (except C. freundii) and their stably derepressed mutants, whereas basal mutants were sensitive (MIC 2-8 mg/l). Carbenicillin, ticarcillin, mezlocillin, piperacillin (and ampicillin for C. freundii) were active against both inducible and basal organisms (MIC less than 16 mg/l), but inactive against the derepressed mutants (MICs usually greater than 64 mg/l). Temocillin inhibited all the organisms, including the stably derepressed mutants, at 16 mg/l. Derepressed S. marcescens, M. morganii and Pr. vulgaris were as susceptible as the inducible strains and basal mutants. MICs of temocillin for derepressed mutants of E. cloacae and C. freundii were 4-16 fold above those for their inducible parent strains, but remained within the clinical range.  相似文献   
1000.
The interaction between oxyhemoglobin (oxyHb) and 5-hydroxytryptamine (5-HT) was investigated in an experimental model of isolated canine internal and common carotid arteries with insertion of stainless steel cannulae. Extraluminal application of 10(-5) M oxyHb induced marked and long-lasting vasoconstriction in the internal carotid but not in the common carotid arteries. The 5-HT-induced vasoconstriction was potentiated significantly in both the internal and common carotid arteries. These potentiations were not influenced by the presence or absence of endothelium, a finding which was confirmed by vascular responses to intraluminal acetylcholine. It is concluded that the interaction between extraluminal oxyHb and intraluminal 5-HT may be one of the possible etiological factors behind the chronic phase of vascular spasm following subarachnoid hemorrhage.  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