全文获取类型
收费全文 | 16703篇 |
免费 | 915篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 221篇 |
儿科学 | 427篇 |
妇产科学 | 192篇 |
基础医学 | 2090篇 |
口腔科学 | 635篇 |
临床医学 | 1459篇 |
内科学 | 3188篇 |
皮肤病学 | 342篇 |
神经病学 | 1785篇 |
特种医学 | 1236篇 |
外国民族医学 | 1篇 |
外科学 | 2455篇 |
综合类 | 156篇 |
一般理论 | 4篇 |
预防医学 | 1468篇 |
眼科学 | 318篇 |
药学 | 803篇 |
1篇 | |
中国医学 | 14篇 |
肿瘤学 | 850篇 |
出版年
2021年 | 200篇 |
2020年 | 121篇 |
2019年 | 150篇 |
2018年 | 234篇 |
2017年 | 189篇 |
2016年 | 215篇 |
2015年 | 284篇 |
2014年 | 391篇 |
2013年 | 504篇 |
2012年 | 697篇 |
2011年 | 724篇 |
2010年 | 490篇 |
2009年 | 415篇 |
2008年 | 724篇 |
2007年 | 805篇 |
2006年 | 734篇 |
2005年 | 728篇 |
2004年 | 658篇 |
2003年 | 629篇 |
2002年 | 633篇 |
2001年 | 640篇 |
2000年 | 589篇 |
1999年 | 483篇 |
1998年 | 208篇 |
1997年 | 151篇 |
1996年 | 146篇 |
1995年 | 169篇 |
1994年 | 148篇 |
1993年 | 120篇 |
1992年 | 336篇 |
1991年 | 362篇 |
1990年 | 308篇 |
1989年 | 288篇 |
1988年 | 279篇 |
1987年 | 232篇 |
1986年 | 259篇 |
1985年 | 264篇 |
1984年 | 205篇 |
1983年 | 190篇 |
1982年 | 125篇 |
1981年 | 122篇 |
1980年 | 117篇 |
1979年 | 241篇 |
1978年 | 154篇 |
1977年 | 154篇 |
1975年 | 150篇 |
1974年 | 127篇 |
1973年 | 135篇 |
1972年 | 141篇 |
1970年 | 117篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
81.
Bigger numbers needed! 总被引:1,自引:0,他引:1
H F Becker 《The European respiratory journal》2004,23(5):659-660
82.
Olaf M Hoffmann Doreen Becker Joerg R Weber 《Journal of cerebral blood flow and metabolism》2007,27(11):1792-1797
Alterations of blood flow contribute to major clinical complications in invasive infections such as sepsis and bacterial meningitis. As a unique feature streptococci -- in particular, Streptococcus pneumoniae, the most frequent pathogen in bacterial meningitis -- release hydrogen peroxide (H(2)O(2)) because of the absence of functional catalase. In a 6 h rat model of experimental meningitis, we studied the impact of bacterial H(2)O(2) production on regional cerebral blood flow (rCBF) and intracranial pressure (ICP). Compared to wild-type D39 pneumococci, the increase of rCBF was diminished in meningitis induced by the H(2)O(2) defective SpxB(-) mutant (maximum increase, 135% +/- 17% versus 217% +/- 23% of the individual baseline; P<0.01) or after treatment of D39-induced meningitis with H(2)O(2)-degrading catalase or with tetraethylammonium (TEA), a blocker of calcium-sensitive potassium channels, which mediate H(2)O(2)-induced vasodilation. Catalase did not significantly reduce the remaining rCBF increase caused by SpxB(-), supporting the predominant role of bacterial H(2)O(2). We conclude that in addition to host-sided mediators, bacterial-derived H(2)O(2) acts as a potent vasodilator, which accounts for a certain proportion of the early cerebral hyperperfusion in pneumococcal meningitis. 相似文献
83.
Frank Makowiec Stefan Post Hans-Detlev Saeger Norbert Senninger Heinz Becker Michael Betzler Heinz J. Buhr Ulrich T. Hopt German Advanced Surgical Treatment Study Group 《Journal of gastrointestinal surgery》2005,9(8):1080-1087
Despite decreasing mortality rates, morbidity is still high after pancreatic head resection. Comparative data in the United
States and Europe show a relationship between hospital volume and mortality. Treatment strategies vary frequently, partially
because of the lack of evidence-based data. We performed a multi-institutional analysis in Germany evaluating current numbers,
indications, techniques, and complication rates of pancreatic head resection. Questionnaires were completed by seven high-volume
surgical departments regarding quantitative and qualitative aspects of pancreatic head resections in the period from 1999
to 2004 (five prospective and two retrospective institutional databases). A total of 1454 pancreatic head resections (944
for malignancy) were reported. Mean annual hospital volume ranged from 14 to 52 (10 to 43 in malignancy). Mortality was between
1.1% and 4.8%, morbidity was between 24% and 46%, and pancreatic leakage was between 9% and 20%. In malignant disease, all
centers perform standard lymphadenectomy and regard arterial infiltration as a contraindication for resection. However, the
rate of portal vein resection varied from 0% to 28%. No consensus is seen on the type of surgery for malignancy and chronic
pancreatitis. After resection for pancreatic cancer less than one fourth of the patients receive adjuvant therapy. The results
of our analysis in Germany confirm that pancreatic head resection can be performed with low mortality in specialized units.
Variations in indications, operative technique, and perioperative care may demonstrate the lack of evidence-based data and/or
personal and institutional experience. The low number of patients receiving adjuvant therapy after resection of pancreatic
cancer suggests that more efforts must be made to establish novel adjuvant therapies under randomized study conditions.
Presented at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–18,
2005 (oral presentation). 相似文献
84.
M Morcos B Fohr J Tafel F Pfisterer A Hamann P Humpert H Bode V Schwenger M Zeier C Becker C Kasperk T Schilling H P Hammes A Bierhaus P P Nawroth 《Experimental and clinical endocrinology & diabetes》2007,115(5):292-297
CONTEXT: Central Cushing's syndrome is not always curable by surgery or radiation of the pituitary. Medical treatment is often not possible or effective. Some studies revealed beneficial effects of the PPARgamma (Peroxisome-Proliferator-Activator- Receptor-gamma)-agonist rosiglitazone (RG) in in vitro studies, animal models and short term clinical studies. OBJECTIVE: of this study was to observe the long-term effects of RG-treatment on cortisol- and ACTH -secretion, clinical outcomes and morphological changes of the pituitary in patients with persistent ACTH-overproduction despite previous operation and radiation. DESIGN, SETTING AND PATIENTS: 14 patients with persistent central ACTH -production were included and monitored over a period up to 12 months. RG was administered daily and increased to a maximum dosage of 24 mg daily, according to the response of ACTH and cortisol secretion. ACTH and cortisol were measured at least every 4 weeks during RG treatment. RESULTS: Patients were treated between 4 and 12 months with RG (mean 6.8 months). Compared to baseline, ACTH- and cortisol levels dropped significantly (p<0.01) after 12, 16, 20, 24 and 28 weeks but thereafter rose again during the study period, despite continuous RG- treatment and dose increase up to the maximum dosage. This was paralleled by reocurrence of clinical symptoms. MRI-scans were performed in 6 patients because of persisting visible adenoma, but showed no morphological changes. CONCLUSION: RG seems not to be a long-term treatment option for patients with persistent central ACTH-evcess. Though, in order to reduce perioperative complications, short term treatment of patients could be an alternative. 相似文献
85.
Adult medulloblastoma: review of 13 cases with emphasis on MRI 总被引:8,自引:1,他引:7
Medulloblastomas are generally associated with childhood, but 14–30% occur in adults, accounting for 1% of adult central nervous system tumors. While approximately one third of adult medulloblastomas present as vermian tumors similar to those seen in childhood, the majority differ substantially from the childhood variety. In this series of 13 patients, 5 had lateral, seemingly extra-axial masses in the cerebellopontine angle or at the tentorium, simulating meningiomas or acoustic neuromas, but angiographic hypovascularity in 2 of the latter suggested a diagnosis other than meningioma. Of 4 paramedian tumors, 3 diffusely infiltrated the cerebellar white matter, showed little or no gadolinium enhancement and were not associated with hydrocephalus. Hydrocephalus was present in less than half of our patients; in childhood the reported incidence is 85–100%. A possible association with pregancy was noted. 相似文献
86.
87.
Detection of Marek's disease virus antigens and DNA in feathers from infected chickens 总被引:1,自引:0,他引:1
Two novel tests, enzyme-linked immunosorbent assay (ELISA) and dot-blot hybridization, were developed to detect and quantify the antigens and DNA of Marek's disease virus (MDV) in feather tips from infected chickens. In both methods, buffered extracts of the feathers served as the same test material. The ELISA technique was compared to the conventional agar-gel precipitation (AGP) test, using the same convalescent serum from a MDV-infected bird. Of 86 feather samples tested, 34 were negative by both methods, while 6 out of 52 were ELISA positive but AGP negative. Viral antigen detection by the AGP and ELISA methods was compared with the detection of MDV DNA by the dot-blot DNA hybridization technique. At an ELISA reading (OD 405) of 0.3 and above, only 5 out of 48 DNA extracts failed to hybridize with the MDV-DNA probe. The use of the radioactively labelled MDV-DNA probe for hybridization with DNA extracts from feather tips of MDV-infected chickens was both sensitive and specific, and there was good correlation among the different tests. 相似文献
88.
The authors developed a statistically based method for determining whether inpatient or outpatient placement is most appropriate for a given patient. This study assesses the method's accuracy by comparing statistical classifications of a random sample of inpatients at five New York State facilities with the classifications of multidisciplinary clinical teams. The statistical method proved to be very strong in screening patients who should not be considered for community placement and in four of the five facilities was also strong in identifying appropriate outpatients. The authors discuss the method's implications for outpatient screening and outpatient programs. 相似文献
89.
Although the partial benzodiazepine receptor inverse agonist, Ro 15-4513, counteracts many ethanol effects, its effect on operant behavior or on ethanol-induced changes in this behavior, remains controversial. In this study, we examined the effects of Ro 15-4513, ethanol, and their interaction on behavior maintained by an FR 20 schedule of food reinforcement. Ro 15-4513 (1.0-4.0 mg/kg) and ethanol (1.5-3.0 g/kg) reduced lever-responding of both male and female mice. The disruptive effect of Ro 15-4513 was of short duration (approximately 10 min), and was greater in male than in female mice. Under equivalent dose and time parameters, ethanol disrupted behavior of both sexes to the same extent. In spite of the disruptive effects of both drugs when given alone, when given after ethanol and prior to testing, Ro 15-4513 attenuated the disruptive effects of ethanol in male mice. The present study extends previous reports by documenting: (1) that the disruptive effect of Ro 15-4513 on mice is of very short duration and occurs at lower doses than previously reported; (2) that, in spite of being disruptive itself, Ro 15-4513 can attenuate the disruptive effects of ethanol on schedule controlled behavior; and (3) that gender is an important consideration in determining the effects of this compound. 相似文献
90.
Neuropathological findings in two siblings with familial erythrophagocytic lymphohistiocytosis (FEL) are reported. Case 1 showed the typical neuropathological findings of FEL with lymphohistiocytic infiltration of the leptomeninges and perivascular spaces. A characteristic erythrophagocytosis was detected in inguinal lymph nodes, lung and bone marrow. Case 2 revealed calcification and necrotic lesions in the brain. In the necrotic areas, parenchymal calcification, vascular medial calcification, and occlusion of many vessels due to subendothelial fibrosis were detected. The areas of necrosis correlated with the distribution of occluded vessels. These changes were most prominent in putamen, internal capsule, thalamus and dentate nucleus. Hypercytokinemia is suspected to be the underlying mechanism for the clinical and laboratory findings in patients with FEL, although the relationship to the vascular pathology is unclear. 相似文献