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   13471篇
  免费   1725篇
  国内免费   21篇
耳鼻咽喉   191篇
儿科学   417篇
妇产科学   276篇
基础医学   1865篇
口腔科学   256篇
临床医学   1659篇
内科学   2716篇
皮肤病学   222篇
神经病学   1344篇
特种医学   399篇
外国民族医学   1篇
外科学   1822篇
综合类   309篇
一般理论   9篇
预防医学   1481篇
眼科学   222篇
药学   1288篇
中国医学   21篇
肿瘤学   719篇
  2021年   227篇
  2020年   141篇
  2019年   222篇
  2018年   285篇
  2017年   173篇
  2016年   206篇
  2015年   210篇
  2014年   305篇
  2013年   381篇
  2012年   617篇
  2011年   633篇
  2010年   339篇
  2009年   343篇
  2008年   605篇
  2007年   606篇
  2006年   577篇
  2005年   561篇
  2004年   534篇
  2003年   502篇
  2002年   508篇
  2001年   492篇
  2000年   436篇
  1999年   394篇
  1998年   164篇
  1997年   167篇
  1996年   154篇
  1995年   157篇
  1994年   139篇
  1993年   133篇
  1992年   393篇
  1991年   331篇
  1990年   297篇
  1989年   287篇
  1988年   323篇
  1987年   282篇
  1986年   254篇
  1985年   209篇
  1984年   241篇
  1983年   185篇
  1982年   134篇
  1981年   106篇
  1980年   106篇
  1979年   188篇
  1978年   119篇
  1976年   125篇
  1975年   122篇
  1974年   119篇
  1973年   109篇
  1972年   113篇
  1970年   108篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
The syndrome of senile gait   总被引:1,自引:0,他引:1  
Summary Infrared computed stroboscopic photometry was used to quantify the kinematic profiles of walking in 10 elderly patients with symmetrical neurological disturbances of gait and in 19 age-matched neurologically healthy people. Clinical examination of the patients revealed similar profiles of walking even though their diagnoses were vascular dementia (2), normal pressure hydrocephalus (2), Alzheimer dementia with possible normal pressure hydrocephalus (2), mixed Alzheimer and vascular dementia (1), peripheral neuropathy (1), Alzheimer dementia with parkinsonian features (1), and un determined (1). Quantitatively, the patients' gait kinematics deviated greatly from control values, but these deviations were statistically attributable to reductions in stride. We suggest that many gait disturbances in elderly people are similar, regardless of etiology, because the characteristics of these gait disturbances are heavily veiled by nonspecific stride-dependent changes that comprise the syndrome of senile gait.  相似文献   
43.
Cattle were immunized with glycoprotein IV (gIV) from bovine herpes virus-1 (BHV-1). Groups of five animals were then given either 2, 3, 4, or 5 doses of interleukin-2 (IL-2) (0.5 microgram/kg) at 12-hr intervals. Animals that received no IL-2 exhibited specific immune responses that are typical for BHV-1 infection, i.e. enhanced specific cytotoxicity, lymphocyte proliferative responses to gIV, and increased gIV-specific (ELISA) and virus-neutralizing antibodies. Treatment of animals with five doses of IL-2 significantly augmented all of these responses except serum neutralization (P less than 0.05). Furthermore, the dose of IL-2 that was selected did not induce any non-specific responses, i.e. hypergamma-globulinaemia, changes in blood chemistry, increased lymphokine-activated killer (LAK) cell activity, changes in mitogen responsiveness or alterations in the phenotypic profile of circulating lymphocytes. Nor were there any clinical changes associated with IL-2 therapy (e.g. depression, pyrexia, diarrhea). Animals that were treated with less than five doses of IL-2 also exhibited elevated immune responses, but they were not significantly different from untreated immunized controls. Interestingly, animals given five doses of IL-2 responded to minor contaminants present in the gIV preparation. This allows speculation that this dose regimen of IL-2 is not only a potent adjuvant for conventional vaccine immunizing doses, but will also allow the use of minute quantities of antigen for immunization.  相似文献   
44.
1. Capsazepine is a synthetic analogue of the sensory neurone excitotoxin, capsaicin. The present study shows the capsazepine acts as a competitive antagonist of capsaicin. 2. Capsazepine (10 microM) reversibly reduced or abolished the current response to capsaicin (500 nM) of voltage-clamped dorsal root ganglion (DRG) neurones from rats. In contrast, the responses to 50 microM gamma-aminobutyric acid (GABA) and 5 microM adenosine 5'-triphosphate (ATP) were unaffected. 3. The effects of capsazepine were examined quantitatively with radioactive ion flux experiments. Capsazepine inhibited the capsaicin (500 nM)-induced 45Ca2+ uptake in cultures of rat DRG neurones with an IC50 of 420 +/- 46 nM (mean +/- s.e.mean, n = 6). The 45Ca2+ uptake evoked by resiniferatoxin (RTX), a potent capsaicin-like agonist was also inhibited. (Log concentration)-effect curves for RTX (0.3 nM-1 microM) were shifted in a competitive manner by capsazepine. The Schild plot of the data had a slope of 1.08 +/- 0.15 (s.e.) and gave an apparent Kd estimate for capsazepine of 220 nM (95% confidence limits, 57-400 nM). 4. Capsazepine also inhibited the capsaicin- and RTX-evoked efflux of 86Rb+ from cultured DRG neurones. The inhibition appeared to be competitive and Schild plots yielded apparent Kd estimates of 148 nM (95% confidence limits, 30-332 nM) with capsaicin as the agonist and 107 nM (95% confidence limits, 49-162 nM) with RTX as agonist. 5. A similar competitive inhibition by capsazepine was seen for capsaicin-induced [14C]-guanidinium efflux from segments of adult rat vagus nerves (apparent Kd = 690 nM; 95% confidence limits, 63 nM-1.45 microM).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
45.
46.
A study of 100 high risk lupus pregnancies.   总被引:2,自引:0,他引:2  
Certain subgroups of lupus patients and those with circulating antiphospholipid antibodies (aPL) in particular, suffer a high rate of fetal loss. Over the past 4 years, we have prospectively studied 100 pregnancies in patients with systemic lupus erythematosus (SLE) and primary antiphospholipid syndrome. In addition to conventional methods of monitoring SLE and fetal development, we have also used Doppler flow assessment of placental perfusion from the 14th wk of pregnancy onward. Patients with the antiphospholipid syndrome and previous history of thrombotic events were treated with daily heparin (10,000 IU) and low-dose aspirin (75 mg). Those without a history of thrombosis were treated with low-dose prednisolone, azathioprine, or hydroxychloroquine. Pregnancy loss was reduced from 81.3% in 101 previous pregnancies to 36.8% in 100 pregnancies managed by us. None of the patients who received hydroxychloroquine throughout the pregnancy presented fetal malformations. Careful management and close monitoring of the lupus pregnancy has substantially improved fetal outcome.  相似文献   
47.
Because the prevalence of the irritable bowel syndrome (IBS) in the general population is unknown, a questionnaire of intestinal symptoms was administered to a stratified random sample of 1058 women and 838 men. Subjects were asked if they had consulted a physician about such symptoms. One or more symptoms occurred frequently in 47% of women and 27% of men. Diagnosable IBS, defined as three or more symptoms, was present in 13% of women and 5% of men. Abdominal pain was the most common symptom, and recurrent intestinal pain was reported by 20% of women and 10% of men. All symptoms were more common in women except runny or watery stools. Most symptoms including pain were unrelated to age. Only half the people with diagnosable IBS had consulted a physician about it. The likelihood of consulting a physician was directly proportional to the number of symptoms and was similar in men and women after controlling for the number of symptoms. Of individual symptoms, the one most strongly associated with consulting was abdominal pain, especially in men. It is concluded that IBS is prevalent at all ages, especially in women, that it is nearly always painful, and that people with multiple symptoms are more likely to consult a physician.  相似文献   
48.
Virus surveillance of Northern Ireland recreational waters, between April 1986 and May 1989 demonstrated widespread enteroviral contamination of coastal and inland waters. In 1986, enteroviruses were detected in 4 of 46 (8.7%) water samples, collected from 6 coastal bathing waters. In 1987, 49 of 107 (45.8%) samples, from 16 coastal bathing waters, yielded enteroviruses; 33 of the enterovirus positive samples passed one or both of the coliform standards outlined by the European Economic Community (EEC) bathing water directive (76/160/EEC). Enteroviruses were also detected in 33 of 39 (84.6%) samples tested from 3 inland recreational waters.  相似文献   
49.
50.
There is a paucity of published information available on extrapulmonary cryptococcosis (EC) in children infected with human immunodeficiency virus, the etiologic agent of the acquired immunodeficiency syndrome. We surveyed investigators in pediatric acquired immunodeficiency syndrome around the country regarding their experience with EC. Investigators from 33 (87%) of 38 institutions responded and information on 13 patients from 11 institutions was analyzed. EC was the acquired immunodeficiency syndrome indicator disease in 9 (69%) of 13 patients. Median age was 8 years with a range of 2 to 17 years. Human immunodeficiency virus risk factors were transfusion (5 patients), hemophilia (4 patients) and perinatal exposure (4 patients). Meningitis, seen in 62% of patients, was the most common clinical manifestation. Although 2 patients with fulminant disease died before therapy was started, 10 (91%) of 11 had a clinical response to amphotericin B with or without flucytosine. Our study indicates a spectrum of EC in pediatric human immunodeficiency virus infection ranging from fulminant, fatal fungemia to chronic meningitis and fever of unknown origin. Cryptococcosis was generally not the cause of death in patients who initially responded to amphotericin B therapy. Optimal antifungal therapy, including the role of fluconazole, warrants further study.  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