全文获取类型
收费全文 | 1248篇 |
免费 | 37篇 |
国内免费 | 51篇 |
专业分类
1336篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 12篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 17篇 |
2014年 | 37篇 |
2013年 | 31篇 |
2012年 | 30篇 |
2011年 | 32篇 |
2010年 | 30篇 |
2009年 | 47篇 |
2008年 | 48篇 |
2007年 | 52篇 |
2006年 | 27篇 |
2005年 | 39篇 |
2004年 | 27篇 |
2003年 | 31篇 |
2002年 | 36篇 |
2001年 | 30篇 |
2000年 | 19篇 |
1999年 | 37篇 |
1998年 | 35篇 |
1997年 | 35篇 |
1996年 | 48篇 |
1995年 | 39篇 |
1994年 | 51篇 |
1993年 | 31篇 |
1992年 | 33篇 |
1991年 | 38篇 |
1990年 | 34篇 |
1989年 | 46篇 |
1988年 | 51篇 |
1987年 | 24篇 |
1986年 | 31篇 |
1985年 | 46篇 |
1984年 | 34篇 |
1983年 | 28篇 |
1982年 | 22篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 7篇 |
排序方式: 共有1336条查询结果,搜索用时 31 毫秒
51.
Mohamed Benichou Gracia Martinez-Reina Felix Romojaro Jean-Claude Pech Alain Latché 《Physiologia plantarum》1995,94(4):629-634
A 36-kDa 1-aminocyclopropane-1-carboxylate (ACC) N-malonyltransferase, which converts the ethylene precursor ACC into the conjugated derivative malonyl-ACC (MACC), has been isolated from etiolated mung bean ( Vigna radiata ) hypocotyls, and partially purified in a four-step procedure. The enzyme is stimulated about 7-fold by 100 m M K+ salts or 0.5 m M Co2+ salts, and is inhibited competitively by D-phenylalanine (Ki = 1.3 m M ) and non competitively by CoASH (0.3 m M ). Beside malonyl-CoA, it is capable to use succinyl-CoA as an acyl donor. The 36-kDa enzyme described here exhibits a lower optimum temperature (40°C) and a 7- or 3-fold lower apparent Km for ACC (68 μ M ) and malonyl-CoA (74 μ M ), respectively, when compared with its 55 kDa isoform already isolated from the same plant material. This data support the idea that several isoforms of ACC N-malonyltransferase exist in plants. These isoforms may play a differential role in regulating the availability of ACC, and consequently the rate of ethylene production, as well as detoxifying cells from D-amino acids. 相似文献
52.
Seroprevalence of B virus (Herpesvirus simiae) antibodies in a naturally formed group of rhesus macaques 总被引:2,自引:0,他引:2
Eighty-two percent of a group of rhesus monkeys removed from Cayo Santiago were seropositive for B virus (Herpesvirus simiae) antibodies. Similar results were obtained from the Cayo Santiago macaque population two decades ago and from feral Indian rhesus monkeys. Thus it is likely that B virus has been enzootic in the Cayo Santiago population since 1938, when the colony was established with stock imported from India. 相似文献
53.
Venkatachalam Sankar Seppan Prakash Rathinasamy Muthusamy Krishnaswami Kamakshi 《Primates; journal of primatology》2000,41(1):89-92
Dracunculiasis, popularly known as Guinea worm disease, has been eradicated from Tamil Nadu, India, and there have been no
indigenous cases reported since 1981. This report describes a female bonnet monkey with dracunculiasis. She presented with
fever and a blister in left hind limb. The blister ruptured on exposure to water and a 7-cm-long worm was extruded. The worm
died before it could be histologically examined. The diagnosis was based on the typical clinical course, which was pathognomonic
of dracunculiasis. Review of literature did not reveal any previous report of dracunculiasis in South Indian bonnet monkeys
(Macaca radiata). This paper raises the question whether wild monkeys might act as reservoirs of human infection and cause resurgence of
the disease in South India.
Animal experiments were approved by the ethical committee of our institute and animal maintenance was according to the recommendations
of the Canadian Council for Experimental Animal Care and the Laboratory Animal Science Association of India. 相似文献
54.
Howard D. Rees Robert W. Bonsall Dr. Richard P. Michael 《Cell and tissue research》1988,254(1):139-146
Summary Target cells for testosterone, dihydrotestosterone, and estradiol in the pituitary gland and genital tract of the male primate were localized by thaw-mount autoradiography, and high performance liquid chromatography was used to identify the metabolites of these steroids in cell nuclei. Castrated rhesus monkeys were injected with 3H-testosterone, 3H-dihydrotestosterone, or 3H-estradiol and killed 60 min later. In the anterior pituitary gland, fewer cells were labeled and less radioactivity was taken up by cell nuclei following the administration of either 3H-testosterone (4% of pars distalis cells and 5 dpm/g DNA) or 3H-dihydrotestosterone (5% of cells and 13 dpm/g DNA) than following the administration of 3H-estradiol (43% of cells and 214 dpm/g DNA). Most of the radioactivity in nuclei was in the form of the unmetabolized parent compound (78–94%). In prostate, seminal vesicles, and penis, 3H-dihydrotestosterone was the predominant form of nuclear radioactivity following both 3H-testosterone (67–90%) and 3H-dihydrostestosterone (94–97%) administration, and both androgens labeled epithelial and smooth muscle cells. In contrast, 3H-estradiol was taken up in unchanged form, by cell nuclei of the genital tract and it labeled connective tissue fibroblasts, but not epithelial cells. Thus, the distributions of target cells for androgens and estrogens were clearly different in all these tissues, and the uptake of testosterone resembled that of its androgenic rather than that of its estrogenic metabolite. 相似文献
55.
56.
Takahiro Tsukahara 《Primates; journal of primatology》1990,31(2):147-156
Grooming initiation among adult males and females of a Japanese macaque troop was analyzed during the non-mating season. Some
gestures (“solicitation”) elicited grooming from partners at a high rate. Grooming initiation patterns were divided into two
main types: (1) a male often solicited a female to groom him immediately after approaching her and was groomed by her; and
(2) a female approached an alpha male selectively, and immediately groomed him. After a female groomed a male, she rarely
solicited him to groom her and instead often moved away from him. These results indicated that males were motivated to be
groomed, while females were more highly motivated to groom. Sex differences in grooming motivation can be explained by sex
differences in the benefit to be groomed. 相似文献
57.
Kees Nieuwenhuijsen Ad J. J. C. Lammers Karel J. de Neef A. Koos Slob 《International journal of primatology》1985,6(1):77-99
Reproductive physiology was studied in female stumptail macaques. Initially the monkeys were housed indoors (individually
and in small groups) and later as one large (92 individuals) social group in an outdoor cage. Most data were collected during
the 4-year outdoor period. Plasma progesterone determination in blood samples taken at weekly intervals allowed estimation
of ovulation and conception dates. The age at first ovulation (X =3.73 years) was positively correlated with body weight at 3 years of age. The average age at first birth was 4.90 years. Gestation
lengths averaged 176.6 days. Following a live birth ovulations returned after a mean interval of 11 months but following an
abortion or still birth this interval was 1 month. Usually a number of ovulatory cycles (X =2.37) preceded a conception. Interbirth intervals (IBIs) in the outdoor cage (X =619.4 days) were significantly longer than IBIs during the indoor period (X =523.1), because indoors the infants were weaned at the age of 7 months, while outdoors weaning occurred more naturally. IBIs
following abortions or still births (X =291.9 days) were significantly shorter than IBIs following live births. Age at first ovulation, age at first birth, IBIs,
and infant production rates were not correlated with dominance rank. Ovarian cycle lengths (X =30.2 days, mode = 28 days) were comparable to previously reported data from laboratory-housed stumptails. No systematic seasonal
fluctuations were found in the onset of sexual maturity, in ovarian cycle lengths, in copulation frequencies, and in distribution
of births. 相似文献
58.
We observed three cases of troop extinction and two cases of female fusion in the wild population of Japanese macaques on Yakushima Island, Japan. Troops P and T decreased in size relatively slowly over a few years until each troop consisted of only three monkeys. Several months later, the remaining adult female of P merged with the adjacent troop S, followed by the remaining female of T. S subsequently also decreased in size and disappeared about 2 years later. In the early stage of troop decline, the mortality rate of adult females was as low as in a growing troop, but the birthrate was quite low. In the late stage of troop decline, the mortality rate increased and the birthrate remained low. An important factor leading to troop extinction may be an increase in population density and the resulting increase in intergroup competition. During the period when P and T declined and ceased to exist, the range of the adopted troop shifted to cover their previous ranges. In the fused troop, there was no severe aggression directed towards the immigrant females or harassment from residents of the adopted troop and there was affiliative social interaction between the immigrant females and resident members. These results agree with previous reports on female fusion: it occurs when the shrinking group consists of one or no adult member, and the immigrant females are not at a severe disadvantage in their adoptive group. A possible benefit for immigrant females is to avoid disadvantage of one-adult group in conflict with conspecifics. A possible cost for immigrant females is transfer to the other troop or to unfamiliar area or both. The cost to transfer to another group may not be high because the members of the adoptive troop are relatively tolerant to immigrants. The cost to transfer to unfamiliar range may be minimized by immigration to the troop whose range shifted to the immigrants' former range. 相似文献
59.
Muhammad Aqib Fahim Nawaz Sadia Majeed Abdul Ghaffar Khawaja Shafique Ahmad Muhammad Asif Shehzad Muhammad Naeem Tahir Muhammad Aurangzaib Hafiz Muhammad Rashad Javeed Muhammad Habib-ur-Rahman Muhammad Munir Usmani 《Physiology and Molecular Biology of Plants》2021,27(5):1073
The present study involved two pot experiments to investigate the response of mung bean to the individual or combined SO42− and selenate application under drought stress. A marked increment in biomass and NPK accumulation was recorded in mung bean seedlings fertilized with various SO42− sources, except for CuSO4. Compared to other SO42− fertilizers, ZnSO4 application resulted in the highest increase in growth attributes and shoot nutrient content. Further, the combined S and Se application (S + Se) significantly enhanced relative water content (16%), SPAD value (72%), photosynthetic rate (80%) and activities of catalase (79%), guaiacol peroxidase (53%) and superoxide dismutase (58%) in the leaves of water-stressed mung bean plants. Consequently, the grain yield of mung bean was markedly increased by 105% under water stress conditions. Furthermore, S + Se application considerably increased the concentrations of P (47%), K (75%), S (80%), Zn (160%), and Fe (15%) in mung bean seeds under drought stress conditions. These findings indicate that S + Se application potentially increases the nutritional quality of grain legumes by stimulating photosynthetic apparatus and antioxidative machinery under water deficit conditions. Our results could provide the basis for further experiments on cross-talk between S and Se regulatory pathways to improve the nutritional quality of food crops.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12298-021-00992-6. 相似文献
60.
本文报告刚刺颚口线虫Gnathostoma hispidum和棘颚口线虫Gnathostoma spinigerum流行学和动物实验。证明我国有40种动物充当它们的第一、二中间宿主和转续宿主,其中30种是这两种病源共同宿主。首次报告猕猴Macaca mulatta可作刚刺颚口线虫的第二中间宿主和转续宿主。用刚刺颚口线虫晚第三期幼虫经皮肤感染家猫和小白鼠均得阳性。调查和实验结果表明刚刺颚口线虫和棘颚口线虫的生物学和流行学特性十分相似,显示它们都是人兽共患的寄生虫。文中讨论刚刺颚口线虫的传播途径和人体感染问题。 相似文献