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   1705篇
  免费   97篇
  国内免费   2篇
耳鼻咽喉   168篇
儿科学   43篇
妇产科学   29篇
基础医学   225篇
口腔科学   79篇
临床医学   100篇
内科学   301篇
皮肤病学   30篇
神经病学   89篇
特种医学   16篇
外科学   218篇
综合类   100篇
预防医学   113篇
眼科学   16篇
药学   143篇
中国医学   12篇
肿瘤学   122篇
  2023年   8篇
  2022年   21篇
  2021年   55篇
  2020年   28篇
  2019年   30篇
  2018年   39篇
  2017年   19篇
  2016年   27篇
  2015年   44篇
  2014年   61篇
  2013年   74篇
  2012年   125篇
  2011年   116篇
  2010年   71篇
  2009年   55篇
  2008年   83篇
  2007年   113篇
  2006年   73篇
  2005年   76篇
  2004年   80篇
  2003年   63篇
  2002年   51篇
  2001年   47篇
  2000年   40篇
  1999年   47篇
  1998年   22篇
  1997年   17篇
  1996年   7篇
  1995年   7篇
  1994年   12篇
  1992年   16篇
  1991年   20篇
  1990年   15篇
  1989年   19篇
  1988年   22篇
  1987年   16篇
  1986年   15篇
  1985年   8篇
  1984年   12篇
  1983年   9篇
  1982年   8篇
  1981年   7篇
  1979年   12篇
  1978年   7篇
  1976年   13篇
  1975年   8篇
  1974年   10篇
  1973年   11篇
  1971年   7篇
  1928年   6篇
排序方式: 共有1804条查询结果,搜索用时 15 毫秒
21.
Purpose:To compare results of a novel “conjunctival frill/smile incision” on surgically induced astigmatism (SIA) and patient discomfort vs conventional trabeculectomy in the initial postoperative period.Methods:Sixty trabeculectomy cases were subjected to either conjunctival frill incision, performed 1.5–2.0 mm from the limbus (study group) or conventional fornix-based conjunctival flap (control group). Corneal astigmatism and suture-induced discomfort were assessed by keratometry and a self-devised patient questionnaire, respectively.Results:Both groups generated a “with the rule” SIA, which was 1.77 vs 2.42 at 1 week and reduced to 1.27 vs 1.8 in the study vs control group, after removal of sutures – both scleral flap releasable and conjunctival at 1 month. Patient discomfort score revealed enhanced comfort in 37% of patients (study group) vs 17% (control group) during the early postoperative period. After 1 month of surgery, good comfort was regained in all cases.Conclusion:This novel suturing technique results in reduced SIA, patient discomfort during the 1st month after trabeculectomy.  相似文献   
22.
Aim:  The present study was carried out to analyze the maternal death rate and its changing trends over a 20-year period in a large referral/teaching institution in Eastern India.
Methods:  A retrospective analysis of maternal deaths was carried out from January 1986 to December 2005 at the Department of Obstetrics and Gynaecology, R. G. Kar Medical College and Hospital, Kolkata, India. Records were divided into four 5-yearly periods: 1986–1990; 1991–1995; 1996–2000; and 2001–2005, for comparison of the trends. The initial interval from 1986 to 1990 was chosen as the reference period.
Results:  The cumulative maternal mortality ratio (MMR) was 599.3 per 100 000 live births. Comparison between the first 5-year period (1986–1991) and the last (2001–2005) showed a statistical significant downward trend in MMR (683.6 vs 474.3; P  < 0.001). Deaths due to direct causes are still the leading cause, accounting for 82.09% of total deaths. Hypertensive disorders (36.14%), hemorrhage (21.91%) and sepsis (19.54%) were still the major causes of direct obstetric deaths throughout the study period. Hypertensive disorders alone showed a substantial decline after the introduction of magnesium sulphate.
Conclusion:  The fall in maternal mortality has been very slow.  相似文献   
23.
24.
Circannual variations in plasma levels of testosterone (T), 17beta-estradiol (E(2)), and 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (DHP) as well as seasonal fluctuations in ovarian steroid synthetic potential were observed in Indian major carp, Labeo rohita. A study was also conducted to examine the mechanism of the development of gonadotropin-induced maturational competence in oocytes of this fish. The present study recorded the lowest values of plasma E(2) and T in L. rohita during the period from October to January. A mild increase in the levels of these steroids observed in February was followed by their rapid rise reaching peak values in April, when the ovary contained mostly the vitellogenic follicles. In the month of May, as the postvitellogenic follicles predominated in the ovary, there was a decline in plasma concentrations of both T and E(2). Low levels of these steroids in plasma remained until January, except a small elevation detectable during June and July (spawning stage). DHP was not detected in the plasma of this fish collected during the period from August to March. Existence of DHP was first recorded in blood in the month of April (vitellogenic stage) and it quickly reached the peak value in May (postvitellogenic stage), followed by a sudden decline in the month of June. Under stimulation of fish pituitary extract (FPE), as a source of gonadotropin, in vitro production of E(2) and T by the vitellogenic follicles was shown to be highest compared to their production rate in other stages, while the postvitellogenic follicles recorded the highest rate of DHP synthesis. Acquisition of oocyte maturational competence (OMC) was shown to develop either by priming the vitellogenic stage fish with a single dose of FPE or by in vitro addition of FPE in culture. In vitro treatment of trilostane, an inhibitor of 3beta-HSD, blocked the FPE-stimulated steroid production but not the development of OMC. Presence of cycloheximide and actinomycin D in the incubation was shown to inhibit FPE-induced development of OMC, indicating the requirement of de novo protein synthesis for this process.  相似文献   
25.
Antisynthetase syndrome (AS) is a rare disease that affects patients with inflammatory myopathies such as polymyositis (PM) and dermatomyositis (DM). In patients with AS, up to 95% of patients develop antisynthetase syndrome-associated interstitial lung disease (AS-ILD). Although AS-ILD commonly occurs in patients with a well-established diagnosis of AS, it can be the first or only manifestation of an occult AS. The frequency of interstitial lung disease (ILD), myopathy, and skin involvement are often dependent on the type of myositis-specific antibodies present. AS-ILD patients who are positive for both anti-Jo-1 and anti-SSA/RO-52 autoantibodies often present with a severe degree of lung restriction on pulmonary function tests and radiologic imaging with an inadequate response toward immunosuppressive therapies. We describe a 65-year-old woman who presents with chronic dyspnea. She was initially diagnosed with corticosteroid-resistant cryptogenic organizing pneumonia based on the radiological findings on her CT chest. Her symptoms did not improve, and she suffered from intolerable corticosteroid-related side effects. Reviews of systems were positive for arthritis and Raynaud's phenomenon. She was found to have elevated inflammatory markers and autoantibodies such as anti-Jo-1, anti-RO-52, and anti-SSA. A diagnosis of AS-ILD resistant to corticosteroid therapy was made. Her lung function improved with combination therapy of mycophenolate and rituximab. Our case highlights that a detailed history and physical exam, compatible radiologic imaging, and autoantibodies are essential for the diagnosis of AS-ILD.  相似文献   
26.
Dermatomyositis (DM) is an idiopathic inflammatory disorder that presents with proximal muscle weakness and typical DM skin changes. DM can involve other organs such as the lung, esophagus, and heart. Diaphragmatic muscle paralysis is an unrecognized clinical presentation of acute DM exacerbation. A 58-year-old man with a history of DM presented to the hospital after sustaining a cardiorespiratory arrest. Before arrest, he had been suffering from progressive dyspnea and muscle weakness. Immunosuppressive therapy of tacrolimus for DM was recently discontinued due to renal toxicity. Bedside ultrasound of the diaphragm while intubated revealed evidence of bilateral diaphragmatic paralysis. After extubation, supine and upright pulmonary function tests (PFT) and sniff test results strengthened the diagnosis of diaphragmatic paralysis. The patient was worked up for an acute DM exacerbation as the likely etiology of the severe diaphragmatic muscle weakness (diaphragmatic paralysis) and ventilatory failure. Skin and muscle biopsy confirmed the diagnosis of active DM. The patient was treated with high dose steroids and mycophenolate mofetil, following which he soon recovered.  相似文献   
27.
Clinical Rheumatology - This narrative review provides an overview of diffuse alveolar hemorrhage (DAH) associated with rheumatologic and autoimmune diseases and their differentiation from...  相似文献   
28.
Substituting an ion of different size from that of the host element introduces lattice strain and defects. However, this mismatch may be significantly reduced by substituting an additional ion with a compensating size relative to the dopant. Such a double substitution might offer better solubility irrespective of the local distortions as well as the formation of defects in the valence states. Fe-substituted ZnO has been widely reported with conflicting results primarily arising from lack of chemical and structural homogeneity originating from preparation techniques, compositional fluctuations, and equivocal comprehension of actual solubility limits of the dopants. In this study, Ag ion has been incorporated in Fe-substituted ZnO to compensate the ionic size of Zn1−x[Fe0.8Ag0.2]xO (0 ≤ x ≤ 0.03125) by determining the solubility limit of the homogeneous material and their corresponding structural, mechanical, optical and magnetic properties have been investigated thoroughly. Co-substitution rearranges the lattice and leads to better crystal structures with tunable properties related to the amount of substitution.

Substituting an ion of different size from that of the host element introduces lattice strain and defects.  相似文献   
29.
The effects of feeding diets with high or low amounts of cholesterol and with low or high levels of mixed plant sterols (sitosterol: campesterol: stigmasterol, 60:35:5) on the daily fecal excretion of acidic steroids were studied in rhesus monkeys. During periods of low dietary plant sterol, total fecal acidic steroid excretion was 43% lower (P less than 0.01) during low dietary cholesterol than during high dietary cholesterol. During periods of high dietary plant sterols the fecal acidic steroid excretion was 113% higher (P less than 0.01) with low dietary cholesterol than with high dietary cholesterol. Addition of mixed plant sterols to the low-cholesterol diet produced nearly a 2-fold increase (P less than 0.005) whereas, such an addition to the high cholesterol diet produced a significant decrease by about 53% (P less than 0.025) in the total fecal acidic steroid excretion. The results suggest that the effect of cholesterol feeding on fecal acidic steroid excretion depends on the level of plant sterols in the diet. This interaction of the effects of cholesterol and plant sterols on the fecal acidic steroid excretion is probably related to the inhibitory effect of plant sterols on cholesterol absorption.  相似文献   
30.
This study explored the role of the proinflammatory chemokines macrophage inflammatory protein (MIP)-1alpha and macrophage chemoattractant protein (MCP)-1 for development of antileishmanial activity. There was substantial inhibition in nitrite generation in Leishmania donovani-infected macrophages. A marked elevation of nitrite generation and induction of inducible nitric oxide (NO) synthase (iNOS) mRNA was found in chemokine-primed parasite-infected macrophages. Tumor necrosis factor-alpha, which is the priming signal for NO production, was also up-regulated under similar experimental conditions. The priming with chemokine inhibited the multiplication of L. donovani amastigotes within the intramacrophageal milieu. The antileishmanial effect of chemokines was almost completely abrogated when the macrophages were preincubated with l-N-monomethyl arginine, the specific inhibitor of iNOS. The results of this investigation suggest that the CC chemokines MIP-1alpha and MCP-1 orchestrate an antileishmanial armamentarium via the induction of an NO-mediated regulatory mechanism to control the intracellular growth and multiplication of the Leishmania protozoan.  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