首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   16574篇
  免费   150篇
  国内免费   2篇
  16726篇
  2023年   126篇
  2013年   728篇
  2012年   117篇
  2011年   123篇
  2010年   199篇
  2009年   392篇
  2008年   173篇
  2007年   161篇
  2006年   120篇
  2005年   119篇
  2002年   133篇
  2000年   117篇
  1999年   145篇
  1998年   139篇
  1997年   130篇
  1996年   157篇
  1995年   163篇
  1994年   122篇
  1993年   255篇
  1992年   217篇
  1991年   211篇
  1990年   240篇
  1989年   415篇
  1988年   364篇
  1987年   469篇
  1986年   406篇
  1985年   411篇
  1984年   333篇
  1983年   276篇
  1982年   315篇
  1981年   350篇
  1980年   325篇
  1979年   326篇
  1978年   380篇
  1977年   425篇
  1976年   439篇
  1975年   464篇
  1974年   314篇
  1973年   175篇
  1972年   175篇
  1971年   171篇
  1970年   173篇
  1969年   140篇
  1968年   138篇
  1967年   130篇
  1964年   164篇
  1960年   116篇
  1959年   116篇
  1958年   132篇
  1957年   163篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
Zusammenfassung Die Radikalausbeute in röntgenbestrahltem L-Leucin -HCl beträgt bei ZimmertemperaturG R=2,2. Kinetische Messungen ergaben Hinweise, daß bei Zimmertemperatur mehr als ein Radikaltyp vorliegt. Aus der Dosiseffektkurve sowie der Kinetik und thermischen Stabilität der Radikale nach höheren Bestrahlungsdosen wird geschlossen, daß ihre Stabilisierung in der Festkörpermatrix durch eine mit steigender Dosis zunehmende Anhäufung von Rekombinationsprodukten verringert wird.
ESR-studies on X-irradiated salts of leucineII. Radical yield and radical kinetics in irradiated L-Leucine · HCl
Summary The free radical yield in L-Leucine · HCl following X-irradiation at room temperature isG R=2,2. The kinetic study shows more than one radical type. From the shape of the dose-yield-curve as well as the kinetics and the annealing behaviour of the radicals after higher irradation doses we assume, that the stabilisation of the radicals by the surrounding lattice is reduced with increasing accumulation of recombination products.


1. Mitteilung: ESR-Untersuchungen zur Radikalstruktur in bestrahltem L-Leucin-HCl. Biophysik5, 14 (1968).

Herrn Prof. Dr. habil.Kh. Lohs möchten wir für die Unterstützung und Diskussion dieser Arbeit danken. Frl. G.Klein danken wit für die umsichtige und sorgfältige technische Mitarbeit.  相似文献   
92.
Summary Mice were sampled from a line selected for increased postweaning weight gain from three to six weeks and from a randombred control line originating from the same base population. Body weights were recorded at each of 14 ages from day 5 to day 98. The Richards and logistic growth functions were fitted to the growth trajectories of each individual mouse by a generalized non-linear least squares procedure. Estimated growth parameters (asymptotic weight, rate, shape of curve, age and weight at inflection, mean absolute growth rate and mean relative growth rate) were computed for each individual. The effects of line, litter within line, sex and line × sex interactions on these estimated parameters were then studied.Both the Richards and logistic functions fitted the data equally well and the plotted trajectories coincided over most of the growth curve. There was excellent agreement between the estimates of asymptotic weight and both age and weight at inflection based on the different functions. However, both functions apparently underestimated the asymptotic weight.Analyses of the line differences showed that selection for postweaning gain increased the mean absolute growth rate over the entire curve but had no effect on the relative growth rate or the shape of the growth curve. Full-sib analyses suggested the presence of considerable genetic variation and some high genetic correlations among the estimated growth parameters.Paper number 2942 of the Journal Series of the North Carolina State University Agricultural Experiment Station, Raleigh, North Carolina. This research was supported in part by Public Health Service Research Grant GM 11546. Computing services were supported by NIH Grant FR-00011.  相似文献   
93.
The social behaviour of T. m. includes ritualized fights. Sperm transfer is achieved by means of a spermatophore deposited on the ground and by the male pulling the female over it. The behaviour and the spermatophore are described and compared to those of other arachnids and the phylogenetical implications are discussed.  相似文献   
94.
A specimen of Ethmorhynchus anophthalmus Meixner 1938 contains a complex of supernumerary genital organs in front of the pharynx. The phenomenon elucidates some traits in the morphogenesis of the atrial organs.
Abkürzungen in den Abbildungen At Atrium genitale - Bu Bursa - Ci Cirrus des Kopulationsorganes - Dc Ductus communis - Ho Hoden - Ke Keimstock - Kop Kopulationsorgan - Ph Pharynx - R Rüssel - Sa Samenblase  相似文献   
95.
Summary A new method of quantification of the acid phosphatase activity assay by means of laser rays along with spectrography and photometry is described. Calculated S values, representing differences between densities of the spectral bands corresponding to Pb and Ag account for the amount of acP activity.The presented laser method enables a relative evaluation of the acP activity in a given region, yielding results which can be objectively expressed by figures.A special advantage of the presented method is, that it allows to compare the individual acP activities in different regions of the investigated organ, which may be of importance for the quantitative chemoarchitectonic of the brain.  相似文献   
96.
Zusammenfassung Mit Hilfe von autoradiographischen und elektrophoretischen Methoden wurde die Dottereinlagerung in den wachsenden Oocyten vonMusca domestica untersucht. Sie beginnt nach 30 min im Autoradiogramm sichtbar zu werden. Durch ihre Färbbarkeit und Markierung konnte die Dotterfraktion im Pherogramm von Ovar und Hämolymphe eines mittleren Wachstumsstadiums (Stadium 3) nachgewiesen werden. Nach Abschlu\ der Vitellogenese tritt sie in der Hämolymphe nicht mehr auf. Die Einlagerung der Dotterproteine wird durch Actinomycin gestört, dagegen läuft ihre Synthese nahezu unbeeinflu\t weiter. Die Transporthemmung kann als bisher unbekannter Nebeneffekt des Actinomycins gedeutet werden.
Synthesis of haemolymph proteine and the uptake of the yolk fraction in the oocyte during Actinomycin-treatment. (Studies onMusca domestica)
Summary By means of radioautographic and electrophoretic techniques yolk protein uptake in the growing oocytes ofMusca domestica was investigated. After 30 min yolk protein becomes visible in the radioautograms. By stainability and labeling the yolk fraction could be demonstrated in the pherogram of ovary and haemolymph in an intermediate developmental stage (stage 3). After the end of vitellogenesis it does not appear in the haemolymph. The yolk protein uptake is inhibited by Actinomycin, but the synthesis goes on nearly as normal. This inhibition can be interpretated as a new accessory effect of Actinomycin.
  相似文献   
97.
Certain temperatures and H-Ion concentrations are necessary for the development of male and female reproductive organs. The differentiation of the reproductive system from undifferentiated cells conforms precisely with data on other species of Stenostomum.
Abkürzungen in den Abbildungen b Bindegewebszelle - c Cilien - cy Cytoplasma - d Darm - de Ductus ejaculatorius - dl Darmlumen - do Dotter - dr Drüsenzellen - lr Lÿckenraum - m Mundöffnung - n Nucleolus - np Nephroporus - o Ovar - p männlicher Genitalporus - pa parenchymatischer Raum - pf periembryonale Flüssigkeit - dse dorsale Epidermis - e dorsolaterale Epidermis - ed extraembryonaler Dotter - ee Epidermiseinstülpung - eh Epidermis +Hautmuskelschlauch - em Embryo - ex Exkretvakuole - f Freßzelle - g Gehirn - ga Gehirnanlagen - gr Granula - h Hautmuskelschlauch - hz Hüzllzelle - kl Versehlußkegel/Klebkegel - in indifferente Zelle - k Kern - kdr Klebdrüsenzelle(n) - kk kollabierter Kanal - Körnerkolbenzelle - kp Kopulationsorgan - ku Kufen - kw Körperwand - l Lichtsinnesorgan - li Linsenkörper - lk lichtbrechende Konkremente im Darmgewebe - ph Pharynx - phr Pharynxregion - pr Zentralkanal des Protonephridialsystems - ps Präspermatide - pu Punktfeld - q Zellquartett - r Riechgruben - rh Rhombuszellenband - rhb Rhabditen - rm Radiärmuskelzelle - rhs Rhabditenschleim - rs resorbierende Darmzelle(n) - s Schale - sc Spermatocyten - se Sekretgang - t Tastborste - ta Auflösungsprodukte des Hodens - te Hoden - to Terminalorgane(e) - tz Teilungszone - v Vakuole - w vermutliches Rudiment des weiblichen Genitalporus  相似文献   
98.
99.
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号