全文获取类型
收费全文 | 580篇 |
免费 | 69篇 |
国内免费 | 26篇 |
出版年
2024年 | 1篇 |
2023年 | 13篇 |
2022年 | 17篇 |
2021年 | 20篇 |
2020年 | 23篇 |
2019年 | 23篇 |
2018年 | 25篇 |
2017年 | 27篇 |
2016年 | 13篇 |
2015年 | 17篇 |
2014年 | 40篇 |
2013年 | 29篇 |
2012年 | 21篇 |
2011年 | 28篇 |
2010年 | 33篇 |
2009年 | 33篇 |
2008年 | 18篇 |
2007年 | 27篇 |
2006年 | 27篇 |
2005年 | 14篇 |
2004年 | 18篇 |
2003年 | 28篇 |
2002年 | 17篇 |
2001年 | 22篇 |
2000年 | 13篇 |
1999年 | 11篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 21篇 |
1991年 | 12篇 |
1990年 | 20篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有675条查询结果,搜索用时 359 毫秒
81.
82.
83.
Thomas Eltz 《Journal of Insect Behavior》1997,10(1):1-11
The relative effects of foraging benefits (food intake) and costs (disturbance = pit destruction) on growth rate and foraging
behavior of larvae of the ant-lionMyrmeleon mobilis were investigated. In a laboratory experiment second-instar larvae were subjected to combinations of three rates of feeding
and three rates of disturbance. Pit relocations were generally rare but occurred more often in starved larvae. Disturbance
rate had no significant effect on pit relocation rate. Feeding rate was a major determinant of the energy allocated in pit
construction and maintenance (positive relationship). In a second experiment third-instar larvae encountered changing rates
of disturbance. Pit size was reduced as a response to increased rates of disturbance. Disturbance had no detectable effect
on growth. In general,M. mobilis larvae were cost-conservative, foragers. 相似文献
84.
GORDON H. YU KAREN S. GUSTAFSON SHIEN-TUNG PAN & R. WESLEY WETHERINGTON 《Cytopathology》2002,13(3):145-151
The distinction of hepatocellular carcinoma (HCC) from benign lesions of the liver in fine needle aspiration (FNA) specimens can be problematic. In an attempt to separate well-differentiated HCC from benign hepatocellular lesions, the presence of tissue fragments displaying peripheral endothelial cells (PE) has been proposed in a previous study as a useful feature in favour of malignancy. In this study, we evaluated slides from 59 cases of liver masses undergoing FNA (19 HCC, 40 benign) and evaluated them for the presence of tissue fragments containing PE. We found that 90% of cases of HCC contained tissue fragments in which PE were either focally present or abundant. However, 68% of cases containing only benign hepatocytes also contained tissue fragments in which PE were at least focally present. In addition, it appears that within the group of benign lesions, the presence of PE was related to the overall cellularity of the specimen rather than the specific nature of the lesion. Thus, the presence of PE in tissue fragments does not, in isolation, appear to be a useful morphological feature for the separation of benign and malignant hepatocellular lesions in FNA material. 相似文献
85.
Three members of the red algal family Halymeniaceae (Thamnoclonium dichotomum (J. Ag.) J. Ag., Codiophyllum flabelliforme (Sond.) Schmitz, and C. decipiens (J. Ag.) Schmitz) are investigated. All are endemic to southern and southwestern Australia, possess basal stalks of substantial size and firmness, and are consistently associated with specific sponge taxa. In each case, the sponges are bonded by collagen-like fibrils to the host cuticle without modifying the algal tissue at the ultrastructural level. Secondary cortication and prominent growth rings occur in the stalks of all three species, and in each the pit plugs between cells become wider, more convoluted and less electron dense with increasing distance from the surface. Such pit plugs are apparently a unique attribute of the stalked Halymeniaceae. The three species share pit plug, sponge association and stalk morphological features but are not otherwise closely related, as they actually represent three distinct genera. 相似文献
86.
OBJECTIVE: The aim of this study was to compare the cytological changes in skin, lymph nodes, liver and bone marrow in patients with lepromatous leprosy. METHODS: Skin lesion, lymph node, liver and bone marrow aspirates were analysed. May-Grunwald-Giemsa (MGG) and Ziehl-Neelsen (Z-N) stains were employed. Comparative cytomorphology was studied. RESULTS: Twenty patients with lepromatous leprosy were studied. Lepra cells (LC) predominated in the skin aspirates of 12 patients with lepromatous leprosy (LL), lymphocytes accompanied LC in eight patients with borderline-lepromatous (BL) leprosy. Three patients of LL leprosy and two of BL leprosy in type 2 reaction additionally had numerous neutrophils. Two patterns of lymph node aspirates were seen: partial replacement with few LC in a reactive lymphoid background (10), complete replacement with either only LC or LC in a background of degenerating neutrophils (10), the latter a feature of type 2 reaction. Liver aspiration was performed in seven patients and of bone marrow in eight patients. Occasional LC were present in five liver-aspirated patients, steatosis and Kupffer cell hyperplasia in four patients, and myelopoiesis in two patients. Bone marrow smears invariably had occasional LC and a relative increase in mature plasma cells; sea-blue histiocytes were seen in six patients. CONCLUSION: Lepra cells predominated in skin and lymph node aspirates with complete replacement. In comparison, liver, bone marrow and lymph node aspirates with partial replacement were dominated by a preponderance of cells native to these organs with only few or occasional LC. 相似文献
87.
OBJECTIVE: The Singapore Breast Screening Pilot Project (SBSPP) was embarked upon (1994-1997) to determine if mammography was useful in early breast cancer detection among Asian women. PATIENTS AND MEASUREMENTS: Of 28 231 women screened, fine needle aspiration cytology (FNAC) was performed in 232 individuals as part of the triple assessment. RESULTS: Absolute and complete sensitivities for the diagnosis of carcinoma were 46.7% and 82.2%, respectively, based on the results of FNAC. Specificity was 63.3%. The inadequate rate was 31%. Five women who were considered cancer-free on triple assessment and, in two cases open diagnostic biopsy during the SBSPP, subsequently developed breast cancer after a median follow-up of 6 years. CONCLUSION: Although our FNAC results compared relatively well with international standards, they reflect a small cohort, and may face additional difficulties in a larger programme. 相似文献
88.
89.
90.
Usefulness of immunocytochemistry using a Breast Marker antibody cocktail targeting P63/cytokeratin7/18/cytokeratin5/14 for fine needle aspiration of the breast: a retrospective cohort study of 139 cases 下载免费PDF全文
S. Tanaka N. Kanomata K. Teramura K. Wakita T. Kunihisa Y. Yano T. Moriya Y. Hayashi 《Cytopathology》2016,27(6):465-471