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   27519篇
  免费   1360篇
  国内免费   233篇
耳鼻咽喉   765篇
儿科学   1778篇
妇产科学   1008篇
基础医学   2005篇
口腔科学   1320篇
临床医学   2151篇
内科学   5701篇
皮肤病学   563篇
神经病学   1718篇
特种医学   1220篇
外国民族医学   2篇
外科学   6040篇
综合类   675篇
现状与发展   1篇
一般理论   7篇
预防医学   858篇
眼科学   878篇
药学   1348篇
  4篇
中国医学   187篇
肿瘤学   883篇
  2024年   24篇
  2023年   275篇
  2022年   400篇
  2021年   720篇
  2020年   482篇
  2019年   584篇
  2018年   820篇
  2017年   723篇
  2016年   975篇
  2015年   981篇
  2014年   1249篇
  2013年   1587篇
  2012年   1888篇
  2011年   1876篇
  2010年   1087篇
  2009年   852篇
  2008年   1626篇
  2007年   1868篇
  2006年   1773篇
  2005年   1739篇
  2004年   1767篇
  2003年   1579篇
  2002年   1423篇
  2001年   696篇
  2000年   657篇
  1999年   442篇
  1998年   204篇
  1997年   163篇
  1996年   129篇
  1995年   75篇
  1994年   57篇
  1993年   41篇
  1992年   45篇
  1991年   32篇
  1990年   25篇
  1989年   34篇
  1988年   26篇
  1987年   16篇
  1986年   23篇
  1985年   13篇
  1984年   16篇
  1983年   8篇
  1982年   9篇
  1980年   6篇
  1979年   9篇
  1978年   8篇
  1977年   7篇
  1974年   8篇
  1972年   8篇
  1967年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Hellenic Journal of Surgery - Hepatolithiasis is the presence of stones within the intrahepatic bile ducts, regardless of common bile duct and gallbladder stones. It is rarely seen in our country...  相似文献   
992.
In this study we have reported a 12-year old girl patient who visited out-patient clinic with the history of headache and convulsion. The patient was diagnosed as miliary tuberculosis and multiple brain tuberculomas. Miliary infiltration was observed in chest x-ray and high-resolution thorax computed tomography (CT), and multiple tuberculomas surrounded with wide edema was observed in Magnetic Resonance Imaging (MRI). Acid-fast bacilli were detected in inducted sputum and gastric fluid. Focal epileptiform activity was seen in electroencephalography (EEG). The patient was administered antitubercular, anti-edema and antiepileptic therapy. The patient had not experienced convulsion for the second time and EEG had been normal; therefore her treatment was completed within 12 months. Chest x-ray and high-resolution thorax CT findings turned to normal and brain MRI findings improved significantly. As a conclusion, tuberculosis disease has very different clinical pattern depending on the organs it involves. The significance of our case is due to the presence of both the miliary tuberculosis and intracranial tuberculomas. The patient was admitted to the hospital due to central nervous system symtoms rather than pulmonary symptoms.  相似文献   
993.
994.
Graefe's Archive for Clinical and Experimental Ophthalmology - Microscale droplets act as coronaviruses (CoV) carriers in the air when released from an infected person and may infect others...  相似文献   
995.
目的:分析评价全国省级抗菌药分级管理目录的合理性、实用性。方法:从各省、市、自治区卫生厅(局)网站收集2012年5月以来发布的省级抗菌药分级管理目录,统计各目录的抗菌药品种名称、数量、分级分类情况,根据国家相关规范分析各省级目录的合理性、实用性以及存在的问题,并提出修订建议。结果:目前已经发布30个省级目录,各个目录收载品种平均147.1(101~194)个,非限制、限制、特殊使用级品种平均分别为:56.4(37~66)、53.7(34~68)、37(24~75)个;分类统计品种数量最多的5类品种为头孢菌素类(29.5个)、依次为青霉素(24.8个)、抗真菌药(14.7个)、喹诺酮类(12.8个)、氨基糖苷类(10个)。总体上目录具备合理性和实用性。存在的问题主要有目录中29个品种无国家药品批准文号,既不合理,也无实用价值;其他问题为分类、分级不当,名称书写错误,等等。结论:应当及时修订,纠正存在的问题,完善目录。  相似文献   
996.
Thiacloprid, a neonicotinoid insecticide, is widely used for controlling various species of pests on many crops. The potential genotoxic effects of thiacloprid on human peripheral blood lymphocytes (PBLs) were investigated in vitro by the chromosome aberrations (CAs), sister chromatid exchanges (SCEs), and cytokinesis‐block micronucleus (MN) assays. The human PBLs were treated with 75, 150, and 300 μg/mL thiacloprid in the absence and presence of an exogenous metabolic activator (S9 mix). Thiacloprid increased the CAs and SCEs significantly at all concentrations (75, 150, and 300 μg/mL) both in the absence and presence of the S9 mix and induced a significant increase in MN and nucleoplasmic bridge formations at all concentrations for 24 h and at 75 and 150 μg/mL for 48‐h treatment periods in the absence of the S9 mix; and at all concentrations in the presence of the S9 mix when compared with the control and solvent control. Thiacloprid was also found to significantly induce nuclear bud (NBUD) formation at 300 μg/mL for 24 h and at 150 μg/mL for 48‐h treatment times in the absence of the S9 mix and at the two highest concentrations (150 and 300 μg/mL) in the presence of the S9 mix. Thiacloprid significantly decreased the mitotic index, proliferation index, and nuclear division index for all concentrations both in the absence and presence of the S9 mix. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 631–641, 2014.  相似文献   
997.
Background: The aim of this study was to evaluate the differences, in terms of visual outcome and treatment needs, between smokers and non-smokers central serous chorioretinopathy (CSCR) patients.

Methods: The files of 252 patients diagnosed with CSCR who had presented to the Retina Unit of the Ophthalmology Clinic at Dicle University Medical School in Turkey were retrospectively evaluated. Eighty-four smokers, with a known history of smoking of at least one pack-year, and 133 non-smokers were included, whereas 35 patients with additional pathologies were excluded from the study.

Results: Of the patients, 192 (88.5%) were male and 25 (11.5%) were female. The mean patient age was 38.8?±?8.1 years (range: 20–68 years). Visual acuity (VA) of the smoker and non-smoker groups was measured as 0.45?±?0.35 and 0.24?±?0.28 logarithm of the minimum angle of resolution (logMar), respectively, at the first visit; 0.19?±?0.29 and 0.06?±?0.14 logMar at the sixth month; and 0.07?±?0.14 and 0.02?±?0.05 logMar at the ninth month. VA measurements at presentation and during all examinations (1th, 6th and 9th month) were significantly different for the two groups. VA was lower in the smoker group. In 27 patients (12.4%), an additional treatment modality was needed. Of the 27 patients, only 8 (6%) were non-smokers, whereas 19 (22.6%) were smokers. There was no difference between groups in the recurrence rate during follow-up (p?=?0.907); 14 (16.7%) smokers and 8 (19.0%) non-smokers experienced a recurrence.

Conclusion: This study has shown that patients selected and who are current smokers have poorer vision and need longer treatment.  相似文献   
998.
Objective: To monitor the changes in corneal thickness during the corneal collagen cross-linking procedure by using isotonic riboflavin solution without dextran in ectatic corneal diseases.

Materials and Methods: The corneal thickness measurements were obtained before epithelial removal, after epithelial removal, following the instillation of isotonic riboflavin solution without dextran for 30?min, and after 10?min of ultraviolet A irradiation.

Results: Eleven eyes of eleven patients with progressive keratoconus (n?=?10) and iatrogenic corneal ectasia (n?=?1) were included in this study. The mean thinnest pachymetric measurements were 391.82?±?30.34?µm (320–434?µm) after de-epithelialization of the cornea, 435?±?21.17?µm (402–472?µm) following 30?min instillation of isotonic riboflavin solution without dextran and 431.73?±?20.64?µm (387–461?µm) following 10?min of ultraviolet A irradiation to the cornea.

Conclusion: Performing corneal cross-linking procedure with isotonic riboflavin solution without dextran might not induce corneal thinning but a little swelling throughout the procedure.  相似文献   
999.
Purpose: The purpose of this study is to evaluate the management of limbal stem cell deficiency (LSCD) secondary to chemical ocular burns.

Materials and methods: The charts of 48 eyes of 40 patients with grade 2 or higher chemical injury were evaluated retrospectively. Subjects with follow-up longer than 1 year were included. Medical treatment, surgical correction of abnormalities of ocular adnexial structures, limbal stem cell transplantation from patient’s fellow eye, from living relatives or from cadaveric donor, amniotic membrane transplantation, conjunctival epitheliectomy, chelation with ethylenediaminetetraacetic acid and penetrating keratoplasty were the treatment modalities. Outcome measures were ocular surface stability and corrected distance visual acuity (CDVA). Failure was defined as the appearance of persistent epithelial defect (nonhealing epithelial defect for more than 2 weeks) with progressive corneal conjunctivalization/vascularization and thinning, and also progression of conjunctivalization to the central 6?mm of the cornea in eyes with subsequent keratoplasty.

Results: The mean age of 31 male and 9 female patients were 32.32?±?12.6 years. LSCD was bilateral in 8 cases. The mean follow-up was 77.2?±?35.1 months. The presentations were in acute phase in 37.5%, in subacute phase in 32.5% and in chronic phase in 30% of the patients. Only 13 of 48 (27.1%) eyes obtained sufficient ocular surface stability through medical treatment; however, only 5 of these eyes achieved CDVA of less than 0.7 logMAR. Limbal stem cell transplantation was performed in 26 eyes as conjunctival limbal autograft, living-related conjunctival limbal allograft and keratolimbal allograft or as a combination of these transplantations. At the last visit, 30 eyes (62.5%) had an intact and stable ocular surface. Clear cornea was achieved in 11 (78.6%) of 14 eyes with grade 2 injury, in 9 (60%) of 15 eyes with grade 3 injury, in 5 (50%) of 10 eyes with grade 4 injury, in 1 (16.6%) of 6 eyes with grade 5 injury and in 1 (33.3%) of 3 eyes with grade 6 injury. The CDVA that was 1.66?±?0.99 logMAR initially improved to 0.87?±?0.85 logMAR at the last visit (p?Conclusion: While patients with low-grade chemical injury seem to benefit quite well from the medical treatment, amniotic membrane transplantation, limbal graft transplantation and subsequent keratoplasty; patients with severe injuries seem to be more prone to failure after all of the available treatment modalities.  相似文献   
1000.
Sperm or testicular tissue cryopreservation is performed in cases of male infertility as a treatment for the preservation of fertility. When these sperm cells are used in assisted reproductive techniques, fertilisation rates, developmental and implantation potential of embryos decrease and the abortion rates increase. In the present work, differences of both phosphorylation and expression levels of p53 and Mitogen‐activated protein kinases (MAPK) proteins were analysed in 61 individual sperm samples before and after cryopreservation. We observed that p53 protein residue at Ser 15 was phosphorylated after cryopreservation. Because MAPK pathway activations may be involved in p53 phosphorylation, MAPK/ERK, Stress‐activated protein kinases (SAPK)/JNK and p38MAPK proteins were also investigated. Analysis showed that p38MAPK phosphorylations increased significantly. However, ERK and JNK expressions and phosphorylations decreased, although the differences were not statistically significant. According to our results, it may be suggested that cryopreservation process activates p53 via p38 MAPK pathway that subsequently causes apoptosis, which may be related to sperm parameters.  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