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   1334715篇
  免费   95765篇
  国内免费   2904篇
耳鼻咽喉   19723篇
儿科学   40230篇
妇产科学   38667篇
基础医学   187259篇
口腔科学   39820篇
临床医学   112638篇
内科学   262426篇
皮肤病学   30225篇
神经病学   106374篇
特种医学   53689篇
外国民族医学   435篇
外科学   208274篇
综合类   31062篇
现状与发展   6篇
一般理论   436篇
预防医学   92065篇
眼科学   31372篇
药学   100071篇
  4篇
中国医学   2987篇
肿瘤学   75621篇
  2018年   11738篇
  2015年   11873篇
  2014年   16686篇
  2013年   25247篇
  2012年   32995篇
  2011年   34859篇
  2010年   20727篇
  2009年   20229篇
  2008年   33569篇
  2007年   36674篇
  2006年   37248篇
  2005年   36003篇
  2004年   35080篇
  2003年   34057篇
  2002年   33584篇
  2001年   63616篇
  2000年   65324篇
  1999年   55388篇
  1998年   14653篇
  1997年   13460篇
  1996年   12944篇
  1995年   12230篇
  1994年   11472篇
  1992年   42769篇
  1991年   41290篇
  1990年   40565篇
  1989年   39556篇
  1988年   36966篇
  1987年   36412篇
  1986年   34903篇
  1985年   33106篇
  1984年   24825篇
  1983年   21056篇
  1982年   12669篇
  1981年   11572篇
  1980年   10775篇
  1979年   23929篇
  1978年   17070篇
  1977年   14837篇
  1976年   13389篇
  1975年   15270篇
  1974年   18082篇
  1973年   17563篇
  1972年   16810篇
  1971年   15717篇
  1970年   14916篇
  1969年   14349篇
  1968年   13463篇
  1967年   12016篇
  1966年   11261篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
High-resolution computed tomography (HRCT) findings in patients with respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) are varied and nonspecific. There is no known report of changes in HRCT findings and respiratory function test results for RB-ILD patients following the cessation of smoking. Five patients with RB-ILD, confirmed by surgical lung biopsy, were retrospectively studied. Each stopped cigarette smoking and did not receive corticosteroid therapy after diagnosis. The clinical symptoms, respiratory function test results and HRCT findings obtained at the final observation were compared with those from the time of diagnosis. Ground-glass opacity and centrilobular nodules corresponding to pathological respiratory bronchiolitis, as well as intralobular fine linear-reticular opacity corresponding to fibrosis involving the subpleural alveolar septa, showed computed tomography-pathological correlations. Both clinical symptoms and the diffusing capacity of the lungs for carbon monoxide improved significantly following smoking cessation, as did ground-glass opacity and centrilobular nodules seen during the initial HRCT examination. Centrilobular nodules and ground-glass opacity, which are the main features of high-resolution computed tomography of respiratory bronchiolitis-associated interstitial lung disease patients and represent pathological respiratory bronchiolitis, can be improved by smoking cessation. The diffusing capacity of the lung for carbon monoxide in respiratory function tests can be also improved.  相似文献   
993.
994.
BACKGROUND: Artemisia species pollen represents a major cause of allergy in Central Europe. Variations in the pollen season, the influence of climate variables and the prevalence of pollinosis to it were analyzed in Poznan, in western Poland between 1995 and 2004. METHODS: A Hirst volumetric spore trap was used for atmospheric sampling. Pollination date trend analysis and Spearman correlation tests were performed. Skin prick tests (SPT) and allergen specific immunoglobulin (lg)E antibody measurements were performed in 676 and 524 patients, respectively. RESULTS: The Artemisia species pollen season grew longer due to a clear advance in the starting day and only a slightly earlier end point; the peak day also came slightly earlier. Rainfall in the first fortnight of July highly influenced pollen season severity. Temperature was directly correlated with daily Artemisia species pollen levels; relative humidity was inversely correlated. Twelve percent of patients had a positive SPT reaction to Artemisia species. Their symptoms were rhinitis and conjunctivitis (15%), atopic dermatitis (15%), chronic urticaria (14.3%), bronchial asthma (2.4%), and facial and disseminated dermatitis (1.3%). Elevated specific IgE concentrations were detected in the sera of 10.1% of patients. CONCLUSIONS: Artemisia species pollen is an important cause of pollinosis in western Poland. Pollen season intensity is highly influenced by rainfall in the previous weeks. Trends towards earlier season starts and longer duration, possibly caused by climate change, may have an impact on the allergic population.  相似文献   
995.
OBJECTIVES: To characterise mycobacterial clinical isolates based on amplification of the rpoB gene. SETTING: One hundred and thirty-five mycobacterial isolates cultured from suspected pulmonary tuberculosis (TB) patients were identified phenotypically. Molecular characterisation of the isolates was performed based on amplification of the rpoB gene, using duplex polymerase chain reaction (DPCR), PCR-restriction fragment length polymorphism (RFLP) and nested PCR-based sequence analysis techniques. RESULTS: The DPCR assay identified 129 of 135 (95.5%) clinical isolates as Mycobacterium tuberculosis complex species. Restriction enzyme analysis of the rpoB PCR product using Hind II identified 134 of the 135 (99.3%) isolates as M. tuberculosis complex, while nested PCR sequence analysis of the rpoB gene identified 133/133 examined isolates (100%) as M. tuberculosis species. No mycobacteria other than M. tuberculosis (MOTT) were detected among the studied isolates. CONCLUSION: DPCR, PCR/RFLP Hind II and nested PCR sequence analysis of the rpoB gene techniques showed comparable efficiency in the characterisation of Mycobacterium isolates. Nested PCR sequence analysis of the rpoB gene was superior to PCR/RFLP for characterisation of suspected M. tuberculosis isolates, while the DPCR technique showed less sensitivity. As PCR-RFLP requires less sophisticated laboratory facilities than nested PCR sequence analysis, it would be more appropriate to be adopted for accurate characterisation of mycobacteria in countries with a weak infrastructure.  相似文献   
996.
SETTING: The assessment of rifampicin (RMP) containing fixed-dose combination (FDC) formulations using in vivo bioequivalence testing is widely accepted. It would be advantageous for both the drug regulatory authorities and drug manufacturers, for optimum minimum blood testing time intervals that encompass all anti-tuberculosis active constituents in the FDC to be established. OBJECTIVE: To determine the optimum blood sampling schedule for testing novel FDC anti-tuberculosis drugs, isoniazid, RMP, pyrazinamide and ethambutol DESIGN: The results of 12 different single-dose, two-way cross-over designs are presented. The studies determined the bioavailability and bioequivalence of RMP-containing FDCs, and conformed with the requirements of the South African national drug regulatory authority for each of the active constituents. RESULTS: The pharmacokinetic parameters to determine bioavailability and the Hauschke method to determine bioequivalence revealed that a six-point time protocol, namely 0, 1, 2, 4, 6 and 8 h, provides a good approximation of the area under the curve, and that an 11-point time protocol of 0, 0.25, 0.5, 1, 1.5, 2, 2.5, 3, 4, 6 and 8 h provided information comparable to the conventional 15 time-points for FDCs containing up to four drugs. CONCLUSION: The findings provide concrete economic benefit and convenience for quality assurance testing of existing and novel FDCs.  相似文献   
997.
Migräne     
Migraine is a prevalent disease that affects women more frequently than men. A particular trigger for migraine is the perimenstrual period. Acute migraine attacks during menstruation are treated similarly to nonmenstrual attacks, e.g., with analgesics or triptans. In women with pure menstrual migraine, short-term prophylaxis can be performed with nonsteroidal anti-inflammatory drugs (NSAIDs), estrogens, or low-dose triptans. During pregnancy migraine improves. After menopause frequency and severity of migraine attacks improve.  相似文献   
998.
999.
BACKGROUND/OBJECTIVE: The efficacy of a direct factor (F)Xa inhibitor, ZK-807834, was compared with indirect inhibition by enoxaparin for inhibition and deaggregation of acute platelet-rich thrombi in a well-characterized porcine carotid injury model. METHODS: A crush injury was performed on a randomly chosen carotid artery and the thrombus allowed to propagate for 30 min. Pigs then received intravenous drug for 35 min: ZK-807834-Dose 1 (40 microg kg(-1) bolus + 1.5 microg kg(-1) min(-1) infusion, n=6); ZK-807834-Dose 2 (20 microg kg(-1) bolus + 0.75 microg kg(-1) min(-1) infusion; n=6); enoxaparin (1 mg kg(-1) bolus; n=6); or saline (n=6). Five minutes after drug initiation, the contralateral artery was injured. Thrombus size was monitored by scintillation detection of autologous 111In-platelets. RESULTS: The prothrombin time ratio was 2.2 +/- 0.1; 1.4 +/- 0.3; 1.2 +/- 0.9 and 1.1 +/- 0.2, respectively. ZK-807834-Dose 1 significantly inhibited carotid platelet deposition (525 +/- 226 x 10(6) cm(-2); P = 0.008), whereas ZK-807834-Dose 2 (2325 +/- 768) and enoxaparin (1236 +/- 383) were not different from saline (2776 +/- 642). Thrombus deaggregation was greatest for animals receiving ZK-807834-Dose 1 (473 +/- 185). Neither ZK-807834-Dose 2 (1588 +/- 480) nor enoxaparin (1618 +/- 686) was different from saline control (2222 +/- 598). CONCLUSIONS: Direct FXa inhibition with ZK-807834, at a prothrombin time ratio of 2.2, effectively inhibits thrombosis and promptly deaggregates thrombi induced by arterial injury. In contrast, indirect FXa inhibition with enoxaparin was ineffective.  相似文献   
1000.
Bisphosphonates are widely used in the treatment of cancer patients with hypercalcemia and bone metastases or in osteoporosis therapy. Current reports have focused on therapy-resistant osteonecrosis of the jaws as a possible side effect of bisphosphonates. Official German drug committees have recently warned about the possibility of these side effects. So far we have experience with 12 patients showing therapy-resistant osteonecrosis of the mandible under bisphosphonate medication, three of whom received oral bisphosphonates for osteoporosis treatment. Presentation of these three cases provides more information on this clinically important side effect of oral bisphosphonate medication, also in osteoporosis therapy.  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