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61.
62.
We studied polymorphism in all species of birds that are presently known to show intraspecific variation in plumage colour. At least three main mechanisms have been put forward to explain the maintenance of polymorphism: apostatic, disruptive and sexual selection. All of them make partly different predictions. Our aims were to investigate evolutionary causes and adaptive functions of colour polymorphism by taking into account a number of ecological and morphological features of polymorphic species. Overall, we found 334 species showing colour polymorphism, which is 3.5% of all bird species. The occurrence of colour polymorphism was very high in Strigiformes, Ciconiiformes, Cuculiformes and Galliformes. Phylogenetically corrected analysis using independent contrasts revealed that colour polymorphism was maximally expressed in species showing a daily activity rhythm extended to day/night, living in both open and closed habitats. All these findings support the hypothesis that colour polymorphism probably evolved under selective pressures linked to bird detectability as affected by variable light conditions during activity period. Thus, we conclude that selective agents may be prey, predators and competitors, and that colour polymorphism in birds may be maintained by disruptive selection. 相似文献
63.
Summary. Nephrectomy in mice provokes a decrease in creatinine clearance (CTNCl) and an increase in urea and specific guanidino compound (GC) concentrations in blood and other tissues. Our purpose was
to investigate the influence of high protein diet (HPD) on CTNCl, urea and GC levels in NX mice. Mice were nephrectomized or sham-operated and subdivided in groups to study five diet conditions.
At the end of each experiment, 10 days and 30 days postsurgery, urine and blood were collected for determination of urea and
GCs, including creatinine. HPD resulted in significantly higher CTNCl values in sham-operated mice than those observed in mice under normal protein diet, 10 days as well as 30 days postnephrectomy.
HPD induced significant increases in plasma urea, guanidinosuccinic acid, argininic acid and α-keto-δ-guanidinovaleric acid concentration 10 days postsurgery but not 30 days postsurgery. HPD coincided with significantly higher
excretion of urea, guanidinosuccinic acid, α-keto-δ-guanidinovaleric acid, creatine, argininic acid and γ-guanidinobutyric acid in sham-operated and nephrectomized mice 10 days postsurgery. Our results show that HPD induces supplementary
(to nephrectomy) increases of urea and GCs in the early postsurgery period but not in the later phase.
Received June 13, 2000 Accepted January 9, 2001 相似文献
64.
65.
Behaviour of interleukin-2 serum levels in advanced non-small-cell lung cancer patients: relationship with response to therapy and survival 总被引:8,自引:0,他引:8
Orditura M Romano C De Vita F Galizia G Lieto E Infusino S De Cataldis G Catalano G 《Cancer immunology, immunotherapy : CII》2000,49(10):530-536
Interleukin(IL)-2 is a T helper (Th) 1 type cytokine that has been shown to play an important role in antitumour immune responses.
In this study, the prognostic significance of serum IL-2 levels was investigated in 60 advanced non-small-cell lung cancer
(NSCLC) patients. IL-2 serum levels were determined before chemotherapy, at the end of chemotherapy and during follow-up,
using a commercially available enzyme-linked immunoadsorbent assay kit. The results were analysed according to the response
to therapy and were used to generate a model predicting overall survival and time to treatment failure. All 60 patients were
shown to have higher IL-2 serum levels than controls (P < 0.0001). Stage IV patients had significantly lower IL-2 levels than stage III patients (P < 0.0001), although they were still significantly higher than controls (P < 0.0001). It is interesting that, when patients were divided into responders and non-responders according to the response
to therapy, the former were shown to have significantly higher pre-chemotherapy levels than the latter (P < 0.0001). Moreover, a further significant increase in IL-2 serum levels (P=0.004) and a significant decrease (P < 0.0001) were shown in responders and non-responders, respectively at the end of the therapy. Using univariate and multivariate
analyses, both overall survival and time to treatment failure were shown to be affected by the mean pathological levels of
IL-2. Furthermore, the prognostic significance of the serum level of IL-2 was confirmed by the stepwise regression analysis.
In conclusion, determination of pre-treatment IL-2 serum levels was shown to be of independent prognostic utility in patients
with advanced NSCLC; therefore, its possible use for prediction of outcome is proposed.
Received: 16 March 2000 / Accepted: 27 July 2000 相似文献
66.
Masini A Ceccarelli-Stanzani D Muscatello U 《Journal of bioenergetics and biomembranes》1983,15(4):217-234
A possible relationship between mitochondrial Mg2+ levels, structural configurations, and functional steady states has been studied in rat liver mitochondria. The results show that the concentration of mitochondrial Mg2+ in respiratory state 4 is definitely higher than in respiratory state 3. The metabolic transition from state 3 to state 4 and vice-versa is associated with reversible influx-efflux of about 10 nmol of Mg2+ per mg protein. The net uptake of this aliquot of Mg2+ is a necessary condition in order for the metabolic transition to state 4, both structurally and functionally, to occur. This process requires a threshold concentration of external Mg2+ greater than 5 mM. The phosphorylative mechanism does not appear to depend on the presence or absence of external Mg2+. The role of Mg2+ on the attainment and maintenance of the structural and functional steady state 4 seems to be correlated with its regulatory effect on the concentration of the mitochondrial Pi. 相似文献
67.
E.tenella感染雏鸡特异性抗体的动态变化和母源免疫的研究 总被引:7,自引:1,他引:7
本实验用斑点酶联免疫试验 (Dot ELISA)检测了E .tenella感染雏鸡特异性抗体、免疫母鸡卵黄和后代血清中特异性母源抗体的动态变化及不同日龄雏鸡的抗球虫水平。结果表明 :(1)雏鸡感染E .tenella后第 6d即可在循环血液中检测到特异性IgG ,于第 18天达到峰值 ,第 30天降至感染后第 7天时的水平。 (2 )母鸡二次免疫后第 5天卵黄中即有高水平的母源抗体 ,免疫母鸡后代 1日龄时母源抗体滴度高达 9.83,与未免疫对照组差异极显著 (P <0 .0 1) ,二者都随着日龄增长降低 ,但免疫组下降幅度很小 ,2 9日龄时仍和对照组 18日龄水平相当。 (3)免疫母鸡后代对再感染的抵抗力显著增强 ,卵囊减少率高达 93%,抗球虫指数和相对增重率都与对照组差异极显著 (P <0 .0 1) ,雏鸡的抗球虫水平随着日龄增长逐渐降低 ;母源抗体、抗球虫指数和相对增重率三者之间两两呈现明显的正相关 ,而这三者又都与卵囊产量呈明显的负相关。 相似文献
68.
69.
External ATP enhanced stomatal opening of Commelina communis L. differently from EDTA. ATP was more effective in opening stomata than EDTA, when both were applied in amounts yielding equivalent free Ca2+ concentration. The stimulation by ATP depended upon its de-phosphorylation and was not due to the P1 released. Hence an energetical contribution of external ATP appears possible. Increase in CO2 concentration increased the stimulation of stomatal opening by ATP and diminished the internal ATP level, ATP/(ADP+AMP) ratio and respiration rate. 相似文献
70.
N. Ohsaki 《Population Ecology》2001,43(1):1-2
This special feature resulted from a symposium entitled "Interactions Between Plants and Their Herbivores," held during the
Meeting of the Society of Population Ecology in Ohmi-Shirahama, Shiga, Japan, in October 1999 (Chairperson of Symposium: Professor
Emeritus E. Kuno of Kyoto University). This theme emerged from discussions by the organizing committee for this symposium:
N. Yamamura, J. Takabayashi, T. Nishida, and N. Ohsaki. Professor Mark D. Rausher of Duke University was invited as a special
lecturer. In this series of reports, five of the seven participants illustrate the variation found in plant–herbivore interactions
and address some problems inherent in current theory. 相似文献