全文获取类型
收费全文 | 9174篇 |
免费 | 674篇 |
国内免费 | 54篇 |
专业分类
耳鼻咽喉 | 209篇 |
儿科学 | 299篇 |
妇产科学 | 240篇 |
基础医学 | 1152篇 |
口腔科学 | 228篇 |
临床医学 | 923篇 |
内科学 | 1880篇 |
皮肤病学 | 58篇 |
神经病学 | 916篇 |
特种医学 | 424篇 |
外国民族医学 | 2篇 |
外科学 | 1382篇 |
综合类 | 166篇 |
一般理论 | 6篇 |
预防医学 | 818篇 |
眼科学 | 139篇 |
药学 | 542篇 |
2篇 | |
中国医学 | 9篇 |
肿瘤学 | 507篇 |
出版年
2021年 | 111篇 |
2020年 | 78篇 |
2019年 | 126篇 |
2018年 | 125篇 |
2017年 | 90篇 |
2016年 | 98篇 |
2015年 | 159篇 |
2014年 | 187篇 |
2013年 | 252篇 |
2012年 | 366篇 |
2011年 | 428篇 |
2010年 | 263篇 |
2009年 | 238篇 |
2008年 | 370篇 |
2007年 | 417篇 |
2006年 | 341篇 |
2005年 | 371篇 |
2004年 | 337篇 |
2003年 | 331篇 |
2002年 | 338篇 |
2001年 | 288篇 |
2000年 | 277篇 |
1999年 | 241篇 |
1998年 | 120篇 |
1997年 | 115篇 |
1996年 | 107篇 |
1995年 | 115篇 |
1994年 | 114篇 |
1993年 | 101篇 |
1992年 | 215篇 |
1991年 | 217篇 |
1990年 | 212篇 |
1989年 | 216篇 |
1988年 | 203篇 |
1987年 | 207篇 |
1986年 | 200篇 |
1985年 | 182篇 |
1984年 | 139篇 |
1983年 | 118篇 |
1982年 | 83篇 |
1980年 | 77篇 |
1979年 | 130篇 |
1978年 | 99篇 |
1977年 | 71篇 |
1976年 | 84篇 |
1975年 | 86篇 |
1974年 | 79篇 |
1973年 | 76篇 |
1972年 | 90篇 |
1971年 | 75篇 |
排序方式: 共有9902条查询结果,搜索用时 15 毫秒
91.
DL?MagerEmail author AD?Haffajee PM?Devlin CM?Norris MR?Posner JM?Goodson 《Journal of translational medicine》2005,3(1):27
Background
The purpose of the present investigation was to determine if the salivary counts of 40 common oral bacteria in subjects with an oral squamous cell carcinoma (OSCC) lesion would differ from those found in cancer-free (OSCC-free) controls. 相似文献92.
OBJECTIVE: To compare and contrast benign and malignant lesions of the breast that have similar appearances on fine-needle aspiration cytology and that constitute diagnostic pitfalls. DESIGN: The cytology files (dated November 1995 through May 1998) of the Beth Israel Deaconess Medical Center were searched to identify cases of breast fine-needle aspiration biopsies that were highly cellular and composed of bland-appearing spindle/columnar cells and that could represent either epithelial or stromal cells; these cases were reported as indeterminate (atypical/suspicious) and had subsequent excisional biopsies taken. RESULTS: Four such cases were found. Two were fibroadenomas and 2 were papillary carcinomas. Their appearances were strikingly similar on aspiration cytology. All cases were prepared with the ThinPrep method. On microscopic examination, all 4 cases were hypercellular and had many single cells and clusters of columnar/elongate cells. Immunocytochemistry proved these cells to be of epithelial origin. At least occasional bipolar stromal cells were seen in the background. The only appreciable difference between the benign and malignant cases was more significant nuclear atypia, which was barely discernible, in the malignant cases. Immunocytochemistry for smooth muscle actin was helpful in 2 cases that had sufficient material. CONCLUSIONS: Some cases of fibroadenomas and papillary carcinomas can be very difficult, if not impossible, to distinguish on fine-needle aspiration cytology. Immunocytochemistry may be helpful if sufficient material is available. To avoid false-negative or false-positive diagnosis on cytology, it is best to report such cases as atypical or suspicious with final diagnosis pending excisional biopsy. 相似文献
93.
Effects of treatment on fertility in long-term survivors of childhood or adolescent cancer 总被引:8,自引:0,他引:8
J Byrne J J Mulvihill M H Myers R R Connelly M D Naughton M R Krauss S C Steinhorn D D Hassinger D F Austin K Bragg 《The New England journal of medicine》1987,317(21):1315-1321
In a retrospective cohort study of survivors of cancer and of controls, we estimated the risk of infertility after treatment for cancer during childhood or adolescence. We interviewed 2283 long-term survivors of childhood or adolescent cancer diagnosed in the period from 1945 through 1975, who were identified at five cancer centers in the United States. Requirements for admission to the study were diagnosis before the age of 20, survival for at least five years, and attainment of the age of 21. In addition, 3270 controls selected from among the survivors' siblings were interviewed. Cox regression analysis showed that cancer survivors who married and were presumed to be at risk of pregnancy were less likely than their sibling controls to have ever begun a pregnancy (relative fertility, 0.85; 95 percent confidence interval, 0.78 to 0.92). Radiation therapy directed below the diaphragm depressed fertility in both sexes by about 25 percent. Chemotherapy with alkylating agents, with or without radiation to sites below the diaphragm, was associated with a fertility deficit of about 60 percent in the men. Among the women, there was no apparent effect of alkylating-agent therapy administered alone (relative fertility, 1.02) and only a moderate fertility deficit when alkylating-agent therapy was combined with radiation below the diaphragm (relative fertility, 0.81). Relative fertility in the survivors varied considerably according to sex, site of cancer, and type of treatment; these factors should be taken into consideration in counseling survivors about the long-term consequences of disease. 相似文献
94.
J. L. Sherwood R. M. Hunger G. C. Keyser L. D. Myers 《Food and Agricultural Immunology》1990,2(3):155-161
The monoclonal antibody technology has provided a means to produce a supply of highly specific uniform antibody which is useful in the detection of plant viruses and which facilitates disease resistance screening. Because of the specificity of a monoclonal antibody to an epitope, a monoclonal antibody may not react to a partially degraded protein. Wheat streak mosaic virus (WSMV) is a member of the potyvirus group and is transmitted by the wheat curl mite Eriophyes tulipae Keifer. The capsid protein of WSMV, like many potyviruses, is degraded in planta. Monoclonal antibodies produced to WSMV reacted to native as well as trypsin treated virions. The antibodies were also useful for evaluation of hard red winter wheat cultivars inoculated with WSMV in the fall or in the spring under field conditions. 相似文献
95.
B J Undem A C Myers D Weinreich 《International archives of allergy and applied immunology》1991,94(1-4):319-324
We have addressed the hypothesis that the excitability of peripheral neurons is affected during immediate hypersensitivity reactions. Guinea pigs were actively sensitized to ovalbumin. The electrical membrane properties of neurons within the superior cervical ganglion, bronchial parasympathetic ganglion and nodose ganglion were evaluated before, during and after antigen challenge. In all preparations, antigen stimulation induced the release of histamine and arachidonic acid metabolites. Our results support the hypothesis that the excitability of sympathetic, parasympathetic and sensory C-type neurons may be increased during immediate hypersensitivity reactions. 相似文献
96.
97.
Selective vulnerability of unmyelinated fiber Schwann cells in nerves exposed to local anesthetics 总被引:1,自引:0,他引:1
H C Powell M W Kalichman R S Garrett R R Myers 《Laboratory investigation; a journal of technical methods and pathology》1988,59(2):271-280
When peripheral nerves of experimental rats are exposed to local anesthetics, distinctive and reproducible pathologic changes occur involving the perineurial sheath and endoneurial contents. Application of intermediate strength concentrations of the local anesthetics, 2-chloroprocaine, lidocaine, etidocaine, and intermediate or high concentrations of procaine to the surface of rat sciatic nerves resulted in the following changes. By 48 hours, the perineurial sheath exposed to the drug was disrupted and became permeable to granulocytes which infiltrated the subjacent endoneurium in conjunction with edema formation in the endoneurial interstitium. Application of 10% procaine to exposed nerve resulted in extensive demyelination. The most striking pathologic change occurring with either intermediate or high doses was accumulation of lipid droplets in Schwann cells, a phenomenon that occurred often in myelin-producing Schwann cells but much less frequently in unmyelinated fiber Schwann Cells. Lipid accumulation appears to be one of several reactive changes that affect Schwann cells of myelinated fibers and is dose-dependent. On the other hand, while reactive changes were infrequently seen in unmyelinated fiber Schwann cells, these cells appeared more susceptible to injury as shown by electron microscopy. Injury to Schwann cells by local anesthetics is temporary because these cells can replicate quickly. Autoradiographic studies of thymidine incorporation 1 week after procaine administration to the sciatic nerve showed intense proliferation of Schwann cells, but no such activity in controls. These findings support the view that their neurotoxic properties may account in some part for the function of local anesthetics, that Schwann cells of small unmyelinated fibers are more vulnerable to these agents than those of myelinated fibers, and that destruction of their supporting cells is followed by vigorous mitotic activity in the endoneurium. 相似文献
98.
Jennifer S Myers Lisa M Bellini Jon B Morris Debra Graham Joel Katz John R Potts Charles Weiner Kevin G Volpp 《Academic medicine》2006,81(12):1052-1058
PURPOSE: To assess internal medicine and general surgery residents' attitudes about the effects of the Accreditation Council for Graduate Medical Education duty hours regulations on medical errors, quality of patient care, and residency experiences. METHOD: In 2005, the authors surveyed 200 residents who trained both before and after duty hours reform at six residency programs (three internal medicine, three general surgery) at five academic medical centers in the United States. Residents' attitudes about the effects of the duty hours regulations on the quality of patient care, residency education, and quality of life were measured using a survey instrument containing 19 Likert scale questions on a scale of 1 to 5. Survey responses were compared using the Student's t-test. RESULTS: The response rate was 80% (159 residents). Residents reported that whereas fatigue-related errors decreased slightly, errors related to reduced continuity of care significantly increased. Additionally, duty hours regulations somewhat decreased opportunities for formal education, bedside learning, and procedures, but there was no consensus that graduates would be less well trained after duty hours reform. Residents, particularly surgical trainees, reported improvements in quality of life and reduced burnout. CONCLUSIONS: Residents in medicine and surgery had similar opinions about the effects of duty hours reform, including improved quality of life. However, resident opinions suggest that reduced fatigue-related errors have been offset by errors related to decreased continuity of care and that the quality of the educational experience may have declined. Quantifying the degree to which regulating duty hours affected errors related to discontinuity of care should be a focus of future research. 相似文献
99.
John S. Pirolo Stephen J. Bresina Lawrence L. Creswell Kent W. Myers Barna A. Szabó Michael W. Vannier Michael K. Pasque 《Annals of biomedical engineering》1993,21(3):199-219
The characterization of regional myocardial stress distribution has been limited by the use of idealized mathematical representations
of biventricular geometry. State-of-the-art computer-aided design and engineering (CAD/CAE) techniques can be used to create
complete, unambiguous mathematical representations (solid models) of complex object geometry that are suitable for a variety
of applications, including stress-strain analyses. We have used advanced CAD/CAE software to create a 3-D solid model of the
biventricular unit using planar geometric data extracted from anex vivo canine heart. Volumetric analysis revealed global volume errors of 4.7%, −1.3%, −1.6%, and −1.1% for the left ventricular
cavity, right ventricular cavity, myocardial wall, and total enclosed volumes, respectively. Model errors for 34 in-plane
area and circumference determinations (mean ±SD) were 5.3±6.7% and 3.8±2.7%. Error analysis suggested that model volume errors
may be due to operator variability. These results demonstrate that solid modeling of theex vivo biventricular unit yields an accurate mathematical representation of myocardial geometry which is suitable for meshing and
subsequent finite element analysis. The use of CAD/CAE solid modeling in the representation of biventricular geometry may
thereby facilitate the characterization of regional myocardial stress distribution. 相似文献
100.