全文获取类型
收费全文 | 15166篇 |
免费 | 1026篇 |
国内免费 | 375篇 |
专业分类
耳鼻咽喉 | 203篇 |
儿科学 | 771篇 |
妇产科学 | 329篇 |
基础医学 | 1529篇 |
口腔科学 | 266篇 |
临床医学 | 1358篇 |
内科学 | 1377篇 |
皮肤病学 | 215篇 |
神经病学 | 771篇 |
特种医学 | 1241篇 |
外国民族医学 | 4篇 |
外科学 | 2392篇 |
综合类 | 1608篇 |
现状与发展 | 3篇 |
预防医学 | 342篇 |
眼科学 | 157篇 |
药学 | 817篇 |
11篇 | |
中国医学 | 110篇 |
肿瘤学 | 3063篇 |
出版年
2024年 | 33篇 |
2023年 | 214篇 |
2022年 | 441篇 |
2021年 | 536篇 |
2020年 | 483篇 |
2019年 | 427篇 |
2018年 | 401篇 |
2017年 | 412篇 |
2016年 | 487篇 |
2015年 | 512篇 |
2014年 | 885篇 |
2013年 | 971篇 |
2012年 | 815篇 |
2011年 | 783篇 |
2010年 | 680篇 |
2009年 | 683篇 |
2008年 | 736篇 |
2007年 | 720篇 |
2006年 | 653篇 |
2005年 | 561篇 |
2004年 | 476篇 |
2003年 | 390篇 |
2002年 | 319篇 |
2001年 | 302篇 |
2000年 | 287篇 |
1999年 | 239篇 |
1998年 | 269篇 |
1997年 | 230篇 |
1996年 | 214篇 |
1995年 | 222篇 |
1994年 | 219篇 |
1993年 | 152篇 |
1992年 | 158篇 |
1991年 | 168篇 |
1990年 | 148篇 |
1989年 | 119篇 |
1988年 | 127篇 |
1987年 | 98篇 |
1986年 | 113篇 |
1985年 | 122篇 |
1984年 | 111篇 |
1983年 | 62篇 |
1982年 | 99篇 |
1981年 | 101篇 |
1980年 | 80篇 |
1979年 | 72篇 |
1978年 | 59篇 |
1977年 | 51篇 |
1976年 | 44篇 |
1974年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Bernd Niederhagen N. Leipner S. Bergé J.-J. von Lindern T. Appel 《Mund-, Kiefer- und Gesichtschirurgie》2000,4(4):217-221
Problem: There is a lack of clear criteria for the use of MR and CT in the diagnosis of head and neck cancer – some of it
is even contradictory. The results of this study should lead to the establishment of more clear criteria. Patients: 165 patients
suffering from head and neck tumors were subjected to a total of 463 CT and 197 MRI examinations. Results: The CT and MRI
staging corresponded in 67% and 60% of the oropharynx tumors, respectively, with the clinical findings. In the case of oral
cavity tumors, the clinical TNM stages were identical with CT and MRI results in 50% and 43% of cases, respectively. In the
case of lymphatic node staging, the frequency of error was slightly higher using MRI, at 27%, compared with the CT rate of
22%. In the evaluation of cervical lymphatic nodes, CT proved to be more sensitive attaining 78% compared to the MRI rate
of 69%. Conclusion: The results provide clear indications as to the MRI and CT examinations. Primary preoperative screening
and post-therapeutic aftercare should be assessed using CT, as should lymphatic node diagnosis in the neck area. In the case
of special problems such as, for example, the relevant bone and periostium infiltration, MR should be considered as a supplementary
examination at a second stage.
相似文献
62.
Proteolysis and invasiveness of brain tumors: Role of urokinase-type plasminogen activator receptor 总被引:2,自引:0,他引:2
Sanjeeva Mohanam Raymond E. Sawaya Masaaki Yamamoto Janet M. Bruner Garth L. Nicholson Jasti S. Rao 《Journal of neuro-oncology》1994,22(2):153-160
Summary The cellular receptor for urokinase-type plasminogen activator (uPAR) in glioblastoma cell lines has been identified and found to be similar to the uPAR expressed by other tumor cell lines. Increased levels of uPAR have been found in primary malignant brain tumor tissues, especially highly malignant glioblastoma, and, to a lesser degree, in malignant astrocytomas, suggesting that this receptor might be involved in efficient activation of pro-uPA and confinement of uPA activity on the cell surface of invading brain tumors. The cell surface uPARs in gliomas could constitute an optimum environment for the generation and activity of plasmin, which is known to play a crucial role in the dissolution of the extracellular matrix during tumor cell invasion.In situ hybridization studies have shown that uPAR mRNA is expressed abundantly in tumor cells and is consistently present at the invasive edges of malignant gliomas. These results imply that uPAR is involved in plasmincatalyzed proteolysis during glioma invasion and that interference with the uPAuPAR interactions could constitute a novel approach for developing therapeutic strategies to counteract invasion of brain tumors. 相似文献
63.
Granulocyte colony-stimulating factor (G-CSF) has been used to reduce the duration and/or degree of neutropenia of different etiologies in recent years. In this study, experience with the use of G-CSF (Neupogen, Roche) after 123 courses of highly myelosuppressive chemotherapy administered to 31 (20 female, 11 male) patients with pediatric solid tumors is reported. G-CSF was initialed at a white blood cell (WBC) count of 918 ± 452/μL (100-2000), at a dose of 7.6 ± 2.3 μg/kgl/d (5-14) subcutaneously for 5.2 ± 2.4 days (2-18). G-CSF was given for afebrile neutropenia after 82 and for febrile neutropenia after 41 courses. Only in two episodes where G-CSF was given for afebrile neutropenia, fever developed. The average hospitalization period for febrile neutropenia was 9.8 ± 3.3 days (5-20). Chemotherapy could be given on scheduled time and dosage in 90% of the courses in which G-CSF was used for afebrile neutropenia. G-CSF was well tolerated. Bone pain was observed in two patients and urticaria in one patient. In conclusion, G-CSF increased the WBC count effectively, there were only two febrile episodes in 82 courses in children receiving G-CSF for afebrile neutropenia, it was well tolerated, and it was found to be feasible for use in a developing country. 相似文献
64.
Martin R. Schneider Michael Schirner Rosemarie B. Lichtner Herrmann Graf 《Breast cancer research and treatment》1996,38(1):133-141
Summary In breast cancer, the survival rate strongly depends on the number of lymph nodes involved. A drug with a specific inhibitory activity on lymph node and organ metastases would therefore be a candidate for adjuvant therapy after surgery. Prostacyclin and its stable analogues have been shown to interfere with certain steps of the metastatic cascade and to inhibit the number of lung colonies after i.v.-inoculation of various tumor cell lines. Our data reveal that cicaprost, a metabolically stable and orally active analogue of prostacyclin, has pronounced antimetastatic effects in a series of spontaneously metastasizing rodent tumors. In the SMT 2a and 13762 MTLn3 mammary carcinomas of the rat, cicaprost given daily from the day of tumor implantation strongly inhibits the number of lung metastases as well as lymph node weights without exerting an effect on the primary tumor. Even starting treatment when palpable primary tumors are present gives a pronounced antimetastatic activity. To demonstrate that cicaprost has an effect on metastases already settled in the respective organ, treatment was started after surgical removal of the primary tumor. In the SMT 2a tumor, a strong inhibition of the number of metastases was shown. Interestingly, a perioperative treatment schedule was also effective in both models used. As primary tumor growth in vivo or proliferation in vitro remained unchanged by cicaprost, its mode of action seems to be related to one or more mechanisms of the metastatic process. In tumor cell lines expressing a functional prostacyclin receptor, stimulated tumor cell migration is inhibited and changes of differentiation status are obvious. In conclusion, cicaprost strongly inhibits lymph node and organ metastases of spontaneously metastasizing rodent mammary tumors with a mode of action different from cytostatic or antihormonal drugs.Presented at the symposium "New Approaches in the Therapy of Breast Cancer", Georgetown University Medical Center, Washington DC, October 1994, generously supported by an education grant from Bristol-Myers Squibb. 相似文献
65.
66.
Human tumors exhibit two fundamentally important characteristics, extensive genetic alteration and clonality. Although it is still unclear to what extent tumors have an elevated mutational burden as compared with normal tissue, their clonality results in their ready detection. Thus, assaying tissues for clonal alterations at frequently mutated microsatellite loci represents a viable approach to cancer diagnosis. The most remarkable extension of this concept is that not only can cancer cells be detected in biological samples, but tumor DNA can also be directly detected in the serum or plasma of patients with some forms of cancer. This recent finding is currently being explored but may represent an important contribution to future diagnostic strategies. 相似文献
67.
Jonas M. Weissbrod Rakesh K. Jain Francis M. Sirotnak 《Journal of pharmacokinetics and pharmacodynamics》1978,6(6):487-503
A lumped compartmental model has been derived to predict methotrexate concentration as a function of time for L1210 cells in BD2F
1
female mice at doses ranging from 3 mg/kg to 400 mg/kg. Using standard methods of parameter estimation as well as experimental determinations, an integrated approach was derived to account for the differences between the subcutaneous (s.c.) and intraperitoneal (i.p.) modes of injection. It was found that a single generalized forcing function can be used to fit plasma concentration after s.c. injection for all doses. Adequate fits (average error<20% while the standard deviation of experimental determinations was±22%) of L1210 cell data after s.c. injection were obtained. The best results were for a maximum facilitated influx constant Vmax
of 0.424 g/min/ml, a Michaelis influx constant Km
of 1,42 g/ml, and a first-order efflux constant of 0.047 min–1.The model simulations were not sensitive to Vmax, Km,and so long as the ratio Vmax/was approximately 9g/ml. The values of V
max
,K
m
,and which were obtained from our analysis of the in vivodata can be explained on the basis of previously performed in vitroexperiments. The parameters obtained from modeling the s.c. data were then applied for i.p. injection data. The resulting fits were adequate (average error<20% while the standard deviation of experimental determinations was±22%). A single generalized forcing function for drug concentration in the peritoneal cavity after i.p. injection for all doses was derived. The application of these results enables the prediction of methotrexate concentration in neoplastic cells at other doses after either s.c. or i.p. injection. 相似文献
68.
D. Schiffer M. T. Giordana A. Mauro G. Racagni F. Bruno S. Pezzotta P. Paoletti 《Acta neuropathologica》1980,49(2):117-122
Summary Experimental cerebral tumors have been induced by transplacental ENU. The morphologic study of the brains of treated rats revealed that cellular hyperplasias appear at the 30th day of extrauterine life in the paraventricular white matter, i.e., before the already known early neoplastic proliferations. Cytofluorimetric investigations failed to demonstrate differences between treated and control rats during the 1st month. On the contrary, adenylate cyclase activity is very high in that period. The duration of the latency period is discussed.This research was supported by Grants No. 79.00678.96 and No. 79.00664.96 of Progetto Finalizzato Control of Neoplastic Growth, Consiglio Nazionale delle Ricerche (C.N.R.), Rome 相似文献
69.
B. P. Hauffa J. Sólyom E. Gláz C. H. L. Shackleton G. Wambach P. Vecsei H. Stolecke J. Homoki 《European journal of pediatrics》1991,150(3):149-153
Infection-triggered, life-threatening salt-loss and hyperkalaemia developed in two male infants with wasting, inappropriately low plasma aldosterone concentrations and elevated plasma renin activity. The presumptive diagnosis of a defective terminal step in aldosterone biosynthesis was made by the presence of large amounts of 11-dehydrotetrahydrocorticosterone and its 18-hydroxylated metabolite (18-OH-THA), free 18-hydroxycorticosterone (18-OH-B) and 18-hydroxytetra-hydrocorticosterone in the urine of both patients. The diagnosis of corticosterone methyl oxidase type II (CMO II) deficiency was confirmed by an elevated urinary 18-OH-THA to tetrahydroaldosterone ratio in one boy and by an elevated plasma 18-OH-B to aldosterone ratio in the other boy. Unknown steroids responsible for the salt-loss were not identified. Sodium supplementation but not short-term high dose oral 9-fluorcortisol (FF) normalized the hyponatraemia in one patient, in whom sodium (Na+)/potassium (K+) co-transport was decreased. Both patients eventually received long-term FF treatment to prevent impairment of longitudinal growth caused by chronic salt-loss. The diagnosis of CMO II deficiency should always be confirmed by elevated precursor-product ratios in urine or plasma, using radioimmunoassays with prior chromatographic separation. Metabolic studies as the short-term response of serum Na+ to high dose FF may not be helpful in differentiating aldosterone biosynthetic defects from endorgan resistance to mineralocorticoids.Dedicated to Professor Dr. Walter Teller, on the occasion of his 60th birthdayPresented in part at the 27th Annual Meeting of the European Society for Paediatric Endocrinology, Copenhagen, Denmark, June 1988 相似文献
70.
We present the cytopathologic findings in seven cases of cavernous hemangiomas of the liver diagnosed by direct "squash" smears made on tissue obtained through image-guided fine-needle biopsy. The diagnosis in each case was confirmed histologically. Utilizing this simple cytologic technique, the morphologic findings in these common hepatic lesions are as accurate and diagnostic as histologic examination. 相似文献