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   43137篇
  免费   3290篇
  国内免费   181篇
耳鼻咽喉   342篇
儿科学   1401篇
妇产科学   834篇
基础医学   5566篇
口腔科学   782篇
临床医学   4227篇
内科学   9342篇
皮肤病学   615篇
神经病学   4391篇
特种医学   1372篇
外国民族医学   1篇
外科学   6287篇
综合类   646篇
一般理论   34篇
预防医学   3731篇
眼科学   832篇
药学   2994篇
  1篇
中国医学   61篇
肿瘤学   3149篇
  2023年   241篇
  2022年   321篇
  2021年   806篇
  2020年   536篇
  2019年   812篇
  2018年   918篇
  2017年   714篇
  2016年   749篇
  2015年   915篇
  2014年   1291篇
  2013年   1825篇
  2012年   2692篇
  2011年   3013篇
  2010年   1651篇
  2009年   1528篇
  2008年   2531篇
  2007年   2826篇
  2006年   2707篇
  2005年   2789篇
  2004年   2579篇
  2003年   2427篇
  2002年   2260篇
  2001年   535篇
  2000年   474篇
  1999年   577篇
  1998年   529篇
  1997年   407篇
  1996年   390篇
  1995年   344篇
  1994年   306篇
  1993年   327篇
  1992年   392篇
  1991年   373篇
  1990年   299篇
  1989年   284篇
  1988年   322篇
  1987年   284篇
  1986年   261篇
  1985年   298篇
  1984年   316篇
  1983年   297篇
  1982年   304篇
  1981年   292篇
  1980年   298篇
  1979年   185篇
  1978年   195篇
  1977年   176篇
  1976年   163篇
  1974年   151篇
  1973年   143篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
We report clinical and pathological data in 56 adolescents presenting with gross hematuria (GH) and 65 presenting with idiopathic nephrotic syndrome (INS). IgA nephropathy (present in 52%) and other mesangial lesions were found in the majority of the 56 patients with GH. Many of these patients had complex urological procedures prior to consideration of a nephrological problem. This often led to significant delays in making the appropriate diagnosis. Pathological lesions in the 65 patients with INS included minimal change NS (MCNS) in 31%, membranous glomerulonephritis (MGN) and focal segmental glomerulosclerosis (FSGS) in 18.5% each, and membranoproliferative GN (MPGN) in 12%. In 47 of the patients with INS, in whom no specific treatment had been given prior to renal biopsy, MCNS and MGN were observed with a similar frequency (26% and 23%, respectively), with FSGS and MPGN being found in 21% and 11%. These results indicate that the pathological lesions in adolescents with INS who undergo a renal biopsy more closely resemble those in adults, and are usually more severe than those in young children. However, it should be noted that our study was retrospective. Hence, there were probably some adolescents with INS who had a successful response to therapy and therefore did not have a renal biopsy performed. Southwest Pediatric Nephrology Study Group (Central Office, Baylor University Medical Center at Dallas, Tex., USA). Director, Ronald J. Hogg; Associate Directors, Fred G. Silva and F. Bruder Stapleton; Statistician, Joan S. Reisch; Administrative Assistant, Kaye Green. Participating Centers—Baylor College of Medicine, Houston, Tex.: Phillip L. Berry, L. Leighton Hill, Sami A, Sanjad, Edith Hawkins; Baylor University Medical Center, Dallas, Tex.: Ronald J. Hogg, Kaye Green; Tulane University Medical Center, New Orleans, La.: Frank Boineau, John E. Lewy, Radhakrishna Baliga, Patrick Walker; University of Arkansas, Little Rock, Ark.: Watson Arnold, Eileen Ellis, Edward Uthman; University of Colorado Health Science Center, Denver, Colo.: Gary M. Lum, Wiliam Hammond; University of Oklahoma Medical Center, Oklahoma City, Okla.: James Wenzl, James Matson, Geoffrey Altshuler, Sarah Johnson; University of Tennessee, Memphis, Tenn.: F. Bruder Stapleton, Shane Roy, III, Robert J. Wyatt, Charles McKay, William Murphy; University of Texas Health Science Center at Dallas, Tex.: Billy S. Arant Jr, Michel Baum, Fred G. Silva, Arthur Weinberg, Craig Argyle, Joseph Rutledge, Ed Eigenbrodt; University of Texas Medical School, Houston, Tex.: Susan B. Conley, Jacques Lemine, Ron Portman, Ann Ince, Regina Verani; University of Texas Health Science Center at San Antonio, Tex.: Michael Foulds, Sudesh Makker, Kanwal Kher, Melanie Sweet, Victor Saldivar, Fermin Tio; University of Texas Medical Branch, Galveston, Tex.: Ben H. Brouhard, Alok Kalia, Luther B. Travis, Lisa Hollander, Tito Cavallo, Srinivasan Rajaraman; University of Utah Medical Center, Salt Lake City; Utah: Eileen Brewer, Richard Siegler, Elizabeth Hammond, Theodore Pysher. Note that this list reflects the investigators' addresses and positions during the period of this study and not necessarily their current situations.  相似文献   
73.
We studied the pharmacokinetics of intravenously and orally administered lamivudine at six dose levels ranging from 0.5 to 10 mg/kg of body weight in 52 children with human immunodeficiency virus infection. A two-compartment model with first-order elimination from the central compartment was simultaneously fitted to the serum drug concentration-time data obtained after intravenous and oral administration. The maximal concentration at the end of the 1-h intravenous infusion and the area under the concentration-time curve after oral and intravenous administration increased proportionally with the dose. The mean clearance of lamivudine (± standard deviation) in the children was 0.53 ± 0.19 liter/kg/h (229 ± 77 ml/min/m2 of body surface area), and the mean half-lives at the distribution and elimination phases were 0.23 ± 0.18 and 2.2 ± 2.1 h, respectively. Clearance was age dependent when normalized to body weight but age independent when normalized to body surface area. Lamivudine was rapidly absorbed after oral administration, and 66% ± 25% of the oral dose was absorbed. Serum lamivudine concentrations were maintained above 1 μM for ≥8 h of 24 h on the twice daily oral dosing schedule with doses of ≥2 mg/kg. The cerebrospinal fluid drug concentration measured 2 to 4 h after the dose was 12% (range, 0 to 46%) of the simultaneously measured serum drug concentration. A limited-sampling strategy was developed to estimate the area under the concentration-time curve for concentrations in serum at 2 and 6 h.  相似文献   
74.
75.
We introduce a new epithelial ovarian carcinoma cell line (UCI 107) from a patient with papillary adenocarcinoma of the ovary who had not been previously treated. The growth characteristics, chemosensitivity, tumorgenicity, cytogenetics, antigen expression, and receptor status were examined. A standardized photometric assay was implemented to determine the response to single drug agents including doxorubicin (ADR), cisplatin (CDDP), and Taxol. Tumorgenicity was determined utilizing female athymic mice implanted either subcutaneously (sc) or intraperitoneally (ip) with 1 × 107 UCI 107 cells. UCI 107 cells grow rapidly in culture with lag phase of approximately 48 hr, population doubling time of 24-36 hr, and saturation density of 4.8 × 105 cells/cm2. The 50% inhibitory concentration values for the chemotherapeutic agents were 0.170, 0.029, and 0.330 μM for ADR, Taxol, and CDDP, respectively. Nude mice produced ip tumors within 15 days, resulting in death from carcinomatosis 40-45 days postimplantation. Subcutaneous tumor nodules (100 mm3 were observed in nude mice 12-13 days post-tumor implantation reaching a maximum tumor volume of approximately 10,000 mm3 by Day 30. The cytogenetic composite karyotype is as follows: 46, X, der (X) t (X;7) (p11;q22), inv dup (1) (q12;q32), t (6;6;11;22) (p21.3;q16;q23.3;q13.3), del (13) (q14.1). The cell line expresses progesterone receptor, increased levels of p53 protein, and cytokeratins. It does not appear to express Her-2/neu protein, estrogen receptor, nor the CA 125 tumor marker. In conclusion, UCI 107 displays unique cellular properties which make it an attractive model for the study of ovarian cancer.  相似文献   
76.
The Child and Adolescent Trial for Cardiovascular Health (CATCH) is a multisite intervention research study that builds on significant progress made in school health education research in the 1980s. The study has three phases: Phase I deals with study design, intervention, and measurement development, Phase II involves the main trial in 96 schools in four states, and Phase III focuses on analysis. The intervention program targets third-fifth grade students and focuses on multiple cardiovascular health behaviors, including eating habits, physical activity, and cigarette smoking. Classroom curricula, school environmental change, and family involvement programs are developed for each grade level and behavioral focus. This paper describes Phase II of CATCH with a rationale for cardiovascular health promotion with youth. The process of change that appears to be necessary for school-based health promotion and that will be tested in CATCH are presented as a framework to guide these efforts.  相似文献   
77.
78.
The present study provides an analysis of the effects of particular patterns of teacher respose to students' entries in dialogue journals. It extended on previous research related to teacher-student instructional discourse by concentrating on written, teacher-student interactions. Second grade children who were participating in a daily dialogue journal activity were randomly subjected to two types of response patterns by their teacher. The results show that a teacher's elaborative responses to student journal entries directly lead to increase written output by students coupled with a distinct process #ophigher order#cp orientation of student entries.  相似文献   
79.
80.
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