全文获取类型
收费全文 | 13957篇 |
免费 | 423篇 |
国内免费 | 3篇 |
出版年
2021年 | 152篇 |
2020年 | 109篇 |
2019年 | 130篇 |
2018年 | 297篇 |
2017年 | 254篇 |
2016年 | 340篇 |
2015年 | 367篇 |
2014年 | 481篇 |
2013年 | 613篇 |
2012年 | 583篇 |
2011年 | 607篇 |
2010年 | 386篇 |
2009年 | 291篇 |
2008年 | 473篇 |
2007年 | 484篇 |
2006年 | 485篇 |
2005年 | 440篇 |
2004年 | 359篇 |
2003年 | 409篇 |
2002年 | 360篇 |
2001年 | 292篇 |
2000年 | 249篇 |
1999年 | 189篇 |
1998年 | 89篇 |
1992年 | 239篇 |
1991年 | 233篇 |
1990年 | 180篇 |
1989年 | 224篇 |
1988年 | 243篇 |
1987年 | 245篇 |
1986年 | 229篇 |
1985年 | 256篇 |
1984年 | 208篇 |
1983年 | 170篇 |
1980年 | 86篇 |
1979年 | 243篇 |
1978年 | 168篇 |
1977年 | 137篇 |
1976年 | 137篇 |
1975年 | 179篇 |
1974年 | 278篇 |
1973年 | 267篇 |
1972年 | 257篇 |
1971年 | 252篇 |
1970年 | 260篇 |
1969年 | 247篇 |
1968年 | 193篇 |
1967年 | 197篇 |
1966年 | 175篇 |
1965年 | 130篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
Molecular genetic analysis in the diagnosis of lymphoma in fine needle aspiration biopsies. II. Lymphomas versus nonlymphoid malignant tumors 总被引:1,自引:0,他引:1
J Lubiński M Chosia K Huebner 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》1988,10(6):399-404
The configurations of immunoglobulin genes and T-cell receptor beta chain genes were analyzed by Southern blotting in DNA derived from nonlymphoid malignant tumors and lymphomas. Gene rearrangements were not detected in any of the 35 cases of nonlymphoid malignant tumors. On the contrary, they were shown in all 14 cases of non-Hodgkin's lymphomas, 2 of 3 cases of Hodgkin's disease and 2 cases diagnosed as non-Hodgkin's lymphoma or angioimmunoblastic lymphadenopathy. The differentiation by light microscopy between lymphoma and nonlymphoid malignant tumors was a diagnostic problem in five cases; the molecular genetic analysis of DNA was contributory in all five diagnostically difficult aspirates. By gene rearrangement studies, the diagnosis of lymphoma was confirmed in two cases and nonlymphoid malignant tumors were accurately indicated in aspirates diagnosed finally as rhabdomyosarcoma (one case) and carcinoma (two cases). 相似文献
104.
The severe strain of potato spindle tuber viroid (s-PSTV) as well as chrysanthemum stunt (CSV) and cucumber pale fruit (CPFV) viroids were found to be transmitted through seed and pollen of the tomato cvs. Rutgers and Najwcze?niejszy. Plants pollinated with a pollen infected with any of these three viroids became systematically infected. Plant, fruit and seed symptoms of viroid infection were noted on sap- and pollen-inoculated plants and the yield of these plants was reduced. Tomato cv. Rutgers plants grown from infected seeds were symptomless although all three viroids were detected in these plants by bioassay and by electrophoresis on 5% polyacrylamide gel. When DNA complementary to s-PSTV RNA was used for a direct viroid detection in seed samples by spot hybridization technique it hybridized not only with s-PSTV RNA but also with CSV RNA as well as with CPFV RNA. 相似文献
105.
J. B. Warchol Ch. Pilgrim W. J. Ginda R. Brelińska 《Histochemistry and cell biology》1988,88(3-6):571-573
Summary Wistar rats were injected intraperitoneally with 2-(14C)deoxyglucose and their thymuses were processed for thaw-mount autoradiography after 5, 10 or 35 min. Highest levels of radioactivity were demonstrated in the thymic medulla (5-fold higher than in the cortex). Scanning of autoradiograms for regional differences in grain densities indicated particularly intense glucose utilization in the cortico-medullary zone. Differences in glucose utilization between individual thymic zones seem to reflect differences in cellular composition, i. e., ratio of stroma cells to thymocytes.Dedicated to Professor Dr. T.H. Schiebler on the occasion of his 65th birthday 相似文献
106.
J Lewin-Kowalik A L Sieroń M Krause J J Barski D Górka 《Acta physiologica Hungarica》1992,79(3):219-231
The present work has a twofold aim: 1. To ascertain whether the stimulative influence of peripheral nerve grafts on injured hippocampal neurons depends on the time lapse after transection and; 2. To examine whether the mentioned effect runs parallel to the time-dependent changes of proteins contents and composition in the submicrosomal fraction from transected rat sciatic nerves. Fluorescence microscope examination revealed that FITC-HRP labeled cells extending their neurites into the implanted peripheral nerve segments were particularly numerous among the hippocampal neurons when 7- and 35-day-old predegenegated distal stumps were used as grafts. Discontinuous SDS-slab polyacrylamide gel electrophoresis of submicrosomal fraction proteins obtained from distal stumps of rat sciatic nerves was performed at the 7, 14, 21 and 35 days after transection. Among the obtained protein fractions the most interesting seem to be the ones of 47 and 54 kDa, which reached maximal levels at the 7th day and the 50 kDa fraction with a maximum at the 35th experimental day. It is possible that the growth promoting power of the employed grafts depends on the presence of proper proteins. 相似文献
107.
Rhida M'Rad Marek Sanak Georges Deschenes Jing Zhou Catherine Bonaiti-Pellie Laurent Holvoet-Vermaut Solange Heuertz Marie-Claire Gubler Michel Broyer Jean-Pierre Grunfeld Karl Tryggvason Marie-Claude Hors-Cayla 《Human genetics》1992,90(4):420-426
Thirty one families with Alport syndrome including 3 families with associated syndromes were studied. The location of the COL4A5 gene, responsible for the Alport syndrome, was determined by linkage analysis with eight probes of the Xq arm and by a radiation hybrid panel. Concordant data indicated the localization of the Alport gene between DXS17 and DXS11. Four deletions and one single base mutation of the COL4A5 gene were detected. Homogeneity tests failed to show any evidence of genetic heterogeneity superimposed on clinical heterogeneity for ophthalmic signs and end-stage renal disease age. 相似文献
108.
W Zgliczyński S Zgliczyński A Makowska J S?owinska-Srzednicka J Janik W Jeske J Walecki 《Endokrynologia Polska》1992,43(3):242-249
Majority of pituitary tumours secrete one of the named hormones: PRL, GH, ACTH, proopiomelanocortine, alpha and beta subunit of TSH, LH, and FSH. Some of those tumours secrete two or more hormones. The aim of this study was to determine the effect of bromocriptine (Parlodel MR and LAR) upon secretion of hormones and tumour size in 10 patients with mixed pituitary tumours. In all patients pituitary and peripheral hormones, CT scan and visual fields were examined before and after treatment with bromocriptine: Parlodel MR and LAR. Bromocriptine treatment decreased PRL secretion in all 10 patients; GH--in all 6 in whom it was increased; TSH--in 2, FSH--in 2 and alpha-subunit in all 6 in whom they were increased. In 5 patients treatment resulted in shrinkage of the tumour mass by 20 to 35%. In all examined subjects clinical improvement was achieved. Our results demonstrate that bromocriptine (Parlodel MR and LAR) is very effective and well tolerated in the treatment of patients with mixed pituitary tumours particularly those with hyperprolactinemia. 相似文献
109.
Normal endothelin 1/2 levels and their correlation with age were evaluated. For clinical application of the endothelin 1/2 RIA test, optimum storage conditions were investigated. Plasma endothelin 1/2 (ET) levels were measured in 36 healthy blood donors, mostly males, of mean age 36 +/- 8 years, subdivided into three age groups: 17-30, 31-40 and above 40 years old. The mean normal ET levels in the three age groups, and corresponding standard deviations, were: 0.58 +/- 0.19, 0.62 +/- 0.31, and 0.80 +/- 0.28 fmol/ml, respectively. The mean ET level for the whole normal population was 0.66 +/- 0.28 fmol/ml. Only differences between mean ET levels for the first and last groups were statistically significant (p < 0.05). Differences between mean ET levels in smokers (53% of total population) and non-smokers, women and men, irrespective of age, were found not to be statistically significant. At this stage of our work, we conclude that other factors than age alone play a role in enhancing ET levels above the age of 41 years. In our study of optimum storage conditions for endothelin 1/2, we found that after one week of storage at -24 degrees C the mean level of ET measured in frozen plasma dropped to 85% of the initial activity, while after the same period the respective decrease in ET activity in frozen extracts was 49%. Over the next two weeks, ET levels in plasma and extracts dropped to 57% and 32% of "zero time" activities, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
110.
W Zgliczyński J Brzeziński A Brzezińska J S?owińska-Srzednicka J Walecki 《Endokrynologia Polska》1992,43(3):210-221
Hypopituitarism can be a result of various lesions of hypothalamus, pituitary stalk, or of the pituitary gland itself. The aim of the study was to assess the value of CT and MRI examinations in determination of the cause of hypopituitarism. Seventeen patients with hypopituitarism (9 women and 8 men) aged 22 to 61 years have been examined. In three cases growth deficiency was observed, 4 women had galactorrhoea, 4 patients had diabetes insipidus, 16 patients had supra-adrenal insufficiency, 14 had signs of hypogonadism and 10 hypothyroidism. In each case plasma concentrations of LH, FSH, PRL, TSH, alpha-subunit, ACTH before and after appropriate stimulation with TRH, metoclopramid, LH-RH, GRF or metyrapon were determined with RIA. Every patient was examined both with CT and MRI (0.5 T Toshiba MRT 50a). All 17 patients had abnormal MR images of hypothalamo-pituitary area, while only 10 of them had abnormalities in their CT scans. In remaining 7 patients the MRI revealed: three cases of congenital malformation of hypophyseal stalk, two cases of empty sella, one posttraumatic lesion of the stalk and one case of granulomatous infiltration of the stalk. We found MRI superior to CT in establishing the case of hypopituitarism. 相似文献